Journal of

Marine Science and Engineering

Article

Expected Effects of Offshore Wind Farms onMediterranean Marine LifeLaura Bray 12 Sofia Reizopoulou 2 Evangelos Voukouvalas 3 Takvor Soukissian 2Carme Alomar 4 Maite Vaacutezquez-Luis 4 Salud Deudero 4 Martin J Attrill 1 andJason M Hall-Spencer 1

1 Marine Institute Plymouth University Plymouth PL4 8AA UK mattrillplymouthacuk (MJA)jasonhall-spencerplymouthacuk (JMH-S)

2 Hellenic Centre for Marine Research Institute of Oceanography Athens-Souniou Ave 467 km AnavissosAttica 19013 Greece sreizhcmrgr (SR) tsoukihcmrgr (TS)

3 European Commission Joint Research Centre (JRC) Institute for Environment and SustainabilityClimate Risk Management Unit Via Enrico Fermi 2749 I-21027 Ispra (VA) Italiaevangelosvoukouvalasextjrceceuropaeu

4 Instituto Espantildeol de Oceanografiacutea Centro Oceanograacutefico de Baleares Moll de Ponent sn07015 Palma de Mallorca Spain calomarbaieoes (CA) maitevazquezbaieoes (MV-L)saluddeuderobaieoes (SD)

Correspondence lbrayhcmrgr Tel +30-229-107-6357

Academic Editor Simon J WatsonReceived 11 December 2015 Accepted 14 February 2016 Published 3 March 2016

Abstract Current climate policy and issues of energy security mean wind farms are being builtat an increasing rate to meet energy demand As wind farm development is very likely in theMediterranean Sea we provide an assessment of the offshore wind potential and identify expectedbiological effects of such developments in the region We break new ground here by identifyingpotential offshore wind farm (OWF) ldquohotspotsrdquo in the Mediterranean Using lessons learned inNorthern Europe and small-scale experiments in the Mediterranean we identify sensitive speciesand habitats that will likely be influenced by OWFs in both these hotspot areas and at a basin levelThis information will be valuable to guide policy governing OWF development and will inform theindustry as and when environmental impact assessments are required for the Mediterranean Sea

Keywords renewable energy Mediterranean Sea ecological impacts marine energy

1 Introduction

The global demand for energy supply continues to increase rapidly [1] Accelerated demographicand economic growth [2] modifications in energy usage as a result of climate change [3] and risingdemands for rural electrification in many Middle East and North Africa (MENA) countries [4] havedramatically increased the energy demands of the Mediterranean region a trend that is set to continueConsequently problems concerning the security of energy supply and the impact of global warmingand ocean acidification as a result of CO2 emissions have stimulated research and development intoenvironmentally sustainable energy This drive is reflected in the Horizons 2020 EU RenewablesDirective (200928EC) with member states required to obtain 20 of their energy consumption fromrenewable energy sources by 2020 [5] Non-EU Mediterranean countries have also recognized the needto decrease reliance on hydrocarbons and most have adopted similar policies [4]

Europe is seeing a rapid expansion of the wind energy sector on land however higher meanwinds speeds due to a reduction in offshore surface roughness [6] and comparatively lower visual andnoise pollution than onshore wind farms [7] has led to a recent expansion of marine wind farms with

J Mar Sci Eng 2016 4 18 doi103390jmse4010018 wwwmdpicomjournaljmse

J Mar Sci Eng 2016 4 18 2 of 17

further planned developments particularly within the North Sea and Baltic regions [8] As of 1 July2014 the EU had a combined offshore capacity of 7343 MW with a further 30000 MW expected by2020 [59] Currently the Mediterranean Sea has no operational offshore wind farms (OWFs) yet this isexpected to go ahead imminently [10]

The environmental effects of OWF construction in the Mediterranean are as yet unknownThe Mediterranean has particular characteristics including minimal tidal ranges high levels ofbiodiversity and endemism [11] and a high potential for range extension of alien species [12]The region is also exposed to a suite of coastal pressures including pollution busy shipping laneseutrophication urban development habitat degradation and overfishing [13] The effects of existingOWFs may not be directly applicable to the Mediterranean highlighting the need for site-specificanalyses before the commencement of large scale offshore developments The aim of this paper is tosystematically assess the biological effects of existing OWFs in Northern European Seas and considerthose in relation to the unique conditions of the Mediterranean basin to horizon-scan for the potentialenvironmental effects and solutions if construction goes ahead

2 Methods

The most important technical criteria for the identification of a suitable OWF sites are windresource availability and bottom depth Evidently for a rational candidate site identification additionaltechnical criteria should be also considered such as distance from shore bottom morphology and typeof sediments electrical grid infrastructure etc however the most important criteria are wind resourceavailability and bottom depth

The wind speed threshold levels and the depth criteria were set in accordance with the EEA (2009)recommendations regarding the economic vitality and the distance for the minimum optical nuisancerequirements of the OWFs respectively Since the current fixed-bottom wind turbine technology(monopile gravity-based jacket and tripod foundations) is limited to water depths up to 50 m thedepth range considered herewith is 20ndash50 m and the lower threshold for the mean annual wind speedat 80 m above mean sea level was set to 5 msacute1 [6] According to the above restrictions using 10-yearresults (1995ndash2004) obtained from the Eta-Skiron model [14ndash16] and the General Bathymetry Chartof the Oceans global relief [1617] potential wind energy sites (model grid points) were identifiedwhile regions with high densities of such point locations were highlighted as offshore wind energyhotspots The Eta-Skiron mesoscale meteorological model is a modified version of the non-hydrostaticEta model and is used for the dynamical downscaling of the ECMWF Era-40 reanalysis data [17] andthe ECMWF operational forecasts with a fine spatial (010˝ ˆ 010˝) and temporal resolution (3 h) [16]An evaluation of the Eta-Skiron model performance as regards the wind power density estimation forthe Mediterranean Sea is presented in Soukissian Papadopoulos [18]

Biological effects resulting from the construction and operation of OWFs were identified ina review of studies in Northern European Seas Peer reviewed literature took precedence and primaryliterature was obtained from several databases including CAB abstracts Google Scholar Web ofScience Science Direct and Scopus Relevant grey literature was also included in the compilation ofinformation and expert opinions were sought from several research institutes and industry experts(references herein) For clarity impacts were separated via taxa (eg birds marine mammalsfish benthos and plankton) Detailed evidence obtained via the literature review is presented ina table format within the supplementary information (Table S1ndashS6) where available specific evidenceregarding the impacts at OWF hotspots will be highlighted

3 Results and Discussion

Although many Mediterranean coastlines seem poorly suited to OWF development some largeareas have exploitable potential including the coasts of the Gulf of Lyons the North Adriatic Seathe entire coastal area of the Gulfs of Hammamet and Gabegraves in Tunisia off the Nile River Delta andthe Gulf of Sidra in Libya (Figure 1) The five hotspots spatially cover the width and breadth of the

J Mar Sci Eng 2016 4 18 3 of 17

Mediterranean Sea Here we consider the potential effects on birds marine mammals fish benthosand plankton throughout the Mediterranean and where available the possible impacts of OWFswithin the specific hotspot regions

J Mar Sci Eng 2016 4 18 3 of 17

and plankton throughout the Mediterranean and where available the possible impacts of OWFs

within the specific hotspot regions

Figure 1 Locations which satisfy offshore wind development requirements of 20ndash50 m depth and an

annual wind speed gt5 msminus1 at a height of 80 m above sea level A Gulf of Lion B North Adriatic Sea

C Gulfs of Hammamet and Gabegraves D Gulf of Sidra E Nile Delta

31 Potential Effects of Mediterranean Offshore Wind Farms on Birds

Wind farms affect resident and migrating birds through avoidance behaviors habitat

displacement and collision mortality but such impacts are difficult to monitor offshore [19] Seabirds

that use the marine environment for foraging or resting may be displaced by OWFs [20] The

Mediterranean has a low diversity of seabirds but these species tend to be long‐lived with low

fecundity traits that often make species vulnerable to abrupt environmental change [1120] (Table 1)

Fortunately most Mediterranean marine birds are listed as ldquoleast concernrdquo on the IUCN red list

although the Audouinʹs gull is listed as ldquonear threatenedrdquo the Yelkouan shearwater as ldquovulnerablerdquo

and the Balearic shearwater as ldquocritically endangeredrdquo [21] All 16 Mediterranean countries have

made commitments to protect these species at a national level [22] With the exception of shearwaters

[23] Mediterranean seabird populations appear to be increasing particularly the yellow‐legged gull

[112425] These increases have been attributed to fish discards and improvements in coastal

conservation [26ndash28] but changes to fishery discard practices following the reform of the Common

Fisheries Policy may reverse this [29]

Studies of Northern European seabird populations have developed vulnerability indices to

indicate seabirds likely to be affected by the presence of OWFs [30ndash32] Using parameters that are

heavily weighted on the risks of collision mortality (flight altitude flight manoeuvrability percentage

of flight time nocturnal flight altitude disturbance by wind farm structures ship and helicopter

traffic and habitat specialization) the NorthBaltic Sea‐based studies assessed 18 of the 29

Mediterranean seabirds Notable exclusions to the list are the endemic species of the Mediterranean

which pose a greater conservation risk due to their small population sizes [33] Garthe and Huumlppop

[13] identify the Black and Red‐throated diver the Sandwich tern and the great Cormorant as the

most sensitive of the Mediterranean seabirds within their index and rated the Black‐legged kittiwake

and the Black‐headed gull as the least sensitive when all parameters were combined Advancing this

approach Furness et al [31] separated the hazards due to collision risk and habitat displacement

They identified the lesser black‐backed gull and the Northern gannet as marine species sensitive to

collision risk and both the red and black‐necked divers as most susceptible to long‐term habitat

displacement These approaches lack any evaluation of species‐specific OWF avoidance behavior and

thus have large caveats attached to their findings The approach of identifying at risk species via

vulnerability indices is useful for the planning stages of OWFs however it does not determine if

construction will have a detectable change in seabird population trends Focus should preferably be

given to understanding any direct effects OWFs will have on foraging success eg diving behavior

Figure 1 Locations which satisfy offshore wind development requirements of 20ndash50 m depth andan annual wind speed gt5 msacute1 at a height of 80 m above sea level A Gulf of Lion B North AdriaticSea C Gulfs of Hammamet and Gabegraves D Gulf of Sidra E Nile Delta

31 Potential Effects of Mediterranean Offshore Wind Farms on Birds

Wind farms affect resident and migrating birds through avoidance behaviors habitatdisplacement and collision mortality but such impacts are difficult to monitor offshore [19]Seabirds that use the marine environment for foraging or resting may be displaced by OWFs [20]The Mediterranean has a low diversity of seabirds but these species tend to be long-lived withlow fecundity traits that often make species vulnerable to abrupt environmental change [1120](Table 1) Fortunately most Mediterranean marine birds are listed as ldquoleast concernrdquo on the IUCNred list although the Audouins gull is listed as ldquonear threatenedrdquo the Yelkouan shearwater asldquovulnerablerdquo and the Balearic shearwater as ldquocritically endangeredrdquo [21] All 16 Mediterraneancountries have made commitments to protect these species at a national level [22] With the exceptionof shearwaters [23] Mediterranean seabird populations appear to be increasing particularly theyellow-legged gull [112425] These increases have been attributed to fish discards and improvementsin coastal conservation [26ndash28] but changes to fishery discard practices following the reform of theCommon Fisheries Policy may reverse this [29]

Studies of Northern European seabird populations have developed vulnerability indices toindicate seabirds likely to be affected by the presence of OWFs [30ndash32] Using parameters that areheavily weighted on the risks of collision mortality (flight altitude flight manoeuvrability percentageof flight time nocturnal flight altitude disturbance by wind farm structures ship and helicopter trafficand habitat specialization) the NorthBaltic Sea-based studies assessed 18 of the 29 Mediterraneanseabirds Notable exclusions to the list are the endemic species of the Mediterranean which posea greater conservation risk due to their small population sizes [33] Garthe and Huumlppop [13] identifythe Black and Red-throated diver the Sandwich tern and the great Cormorant as the most sensitiveof the Mediterranean seabirds within their index and rated the Black-legged kittiwake and theBlack-headed gull as the least sensitive when all parameters were combined Advancing this approachFurness et al [31] separated the hazards due to collision risk and habitat displacement They identifiedthe lesser black-backed gull and the Northern gannet as marine species sensitive to collision risk andboth the red and black-necked divers as most susceptible to long-term habitat displacement Theseapproaches lack any evaluation of species-specific OWF avoidance behavior and thus have largecaveats attached to their findings The approach of identifying at risk species via vulnerability indicesis useful for the planning stages of OWFs however it does not determine if construction will have

J Mar Sci Eng 2016 4 18 4 of 17

a detectable change in seabird population trends Focus should preferably be given to understandingany direct effects OWFs will have on foraging success eg diving behavior and prey characteristicswhich in turn will impact reproductive success juvenile survival and population trends [20]

Table 1 Mediterranean seabird sensitivity assessments highlighting most and least vulnerable speciesaccording to index Y = Yes N = No Red = 10 most vulnerable Mediterranean species within indexBlue = 10 least vulnerable species within index ldquo-rdquo = Index not applied

Common Name Species EndemicListed under

BarcelonaConvention

Wind FarmSensitivityIndex [13]

VulnerabilityIndex forCollision

Impacts [30]

VulnerabilityIndex for

DisturbanceImpacts [30]

Coryrsquos Shearwater(Mediterranean)

Calonectris diomedeadiomedea Y Y - - -

YelkouanShearwater

(Mediterranean)Puffinus yelkouan Y N - - -

Balearic Shearwater Puffinusmauretanicus Y N - - -

European Shag(Mediterranean)

Phalacrocoraxaristotelis desmarestii Y Y - 150 14

Great Comorant Phalacrocorax carbo N N 233 - -

Pygmy Comorant Phalacrocoraxpygmeus N N - - -

Audouinrsquos gull Larus audouinii N Y - - -

Little Gull Hydrcoleus minutus N N 128 - -

Lesser black-backedgull Larus fuscus N N 138 960 3

Slender billed gull Larus genei N Y - - -

Mediterranean gull Larus melanocephalus N Y - - -

Black-headed gull Larus ridibundus N N 75 - -

Caspian gull Larus cachinnans N N - - -

Black leggedkittiwake Rissa tridactyla N N 75 -

Yellow legged gull Larus michahellis N N - - -

Great skua Catharacta skua N N - 320 3

Caspian tern Hydroprogne caspia N N - - -

Common tern Sterna hirundo N N 150 229 8

Little tern Sterna albifrons N N - 212 10

Sandwich tern Sterna sandvicensis N N 250 245 9

Lesser-crested tern Thalasseusbengalensis N N - -

Razorbill Alca torda N N 158 32 14

Atlantic puffin Fratercula arctica N N 150 27 10

European Stormpetrel

Hydrobates pelagicmelitensis Y Y - 91 2

Northern gannet Morus bassanus N N - - -

Osprey Pandion haliaetus N Y - - -

Eleanorersquos falcon Falco eleonorae N Y - - -

Red throated diver Gavia stellata N N 433 213 32

Black throated diver Gavia arctica N N 403 240 32

Great crested grebe Podicep scristatus N N 193 84 8

Red-necked grebe Podiceps grisegena N N 187 - -

Eared grebe Podiceps nigricollis N N - - -

J Mar Sci Eng 2016 4 18 5 of 17

Threats to Mediterranean bird populations are also directed towards migratory speciesWorldwide migratory species are declining in greater numbers than resident populations [34] and theMediterranean basin is a major transit route for Saharan-Eurasian migration as evidenced by both theMediterranean-Black Sea flyway and the Adriatic flyway [3536] Many long-distance bird migrantseg raptors and storks rely on land lift via thermal upwelling for long-distance flight [3738] andavoid broad fronts such as the Mediterranean Sea and the Saharan desert [37] creating bottlenecksat narrow passages of the Mediterranean Sea including Gibraltar the Straits of Sicily Messina (Italy)and the Belen pass (Turkey) [39] Wetlands around the Mediterranean provide suitable stopoversites for long-distance migrants to feed rest and molt [40] Some of the main wetlands around theMediterranean are located within close proximity of potential OWF hotspots particularly the Po Deltain the Northern Adriatic Sea the Nile Delta the Gabegraves Delta and the Camargue Delta in the Gulf ofLion (Figure 2) Due to the bathymetry of the Mediterranean and the steep continental slope of mostcoastlines deltas provide feasible sites for wind farm constructions High densities of avian habitatuse in these regions means that OWF resource overlap will be a key factor in Mediterranean marinespatial planning in regard to OWFs

J Mar Sci Eng 2016 4 18 5 of 17

Black throated

diver Gavia arctica N N 403 240 32

Great crested

grebe

Podicep

scristatus N N 193 84 8

Red‐necked grebe Podiceps

grisegena N N 187 ‐ ‐

Eared grebe Podiceps

nigricollis N N ‐ ‐ ‐

Threats to Mediterranean bird populations are also directed towards migratory species

Worldwide migratory species are declining in greater numbers than resident populations [34] and

the Mediterranean basin is a major transit route for Saharan‐Eurasian migration as evidenced by

both the Mediterranean‐Black Sea flyway and the Adriatic flyway [3536] Many long‐distance bird

migrants eg raptors and storks rely on land lift via thermal upwelling for long‐distance flight

[3738] and avoid broad fronts such as the Mediterranean Sea and the Saharan desert [37] creating

bottlenecks at narrow passages of the Mediterranean Sea including Gibraltar the Straits of Sicily

Messina (Italy) and the Belen pass (Turkey) [39] Wetlands around the Mediterranean provide

suitable stopover sites for long‐distance migrants to feed rest and molt [40] Some of the main

wetlands around the Mediterranean are located within close proximity of potential OWF hotspots

particularly the Po Delta in the Northern Adriatic Sea the Nile Delta the Gabegraves Delta and the

Camargue Delta in the Gulf of Lion (Figure 2) Due to the bathymetry of the Mediterranean and the

steep continental slope of most coastlines deltas provide feasible sites for wind farm constructions

High densities of avian habitat use in these regions means that OWF resource overlap will be a key

factor in Mediterranean marine spatial planning in regard to OWFs

Figure 2 Main Mediterranean wetlands and overlapping OWF potential hotspot areas (adapted from

[41] 1 Ebro Delta 2 Camargue Delta 3 Po Delta 4 Amvrakikos Gulf 5 Prespa Basin 6 Aliakmonas

Delta 7 Evros Delta 8 Gediz Delta 9 Gӧksu Delta 10 Seyhan Delta 11 Nile Delta 12 Gabegraves Delta

13 El Kala

High collision levels of migrating terrestrial birds at well‐lit observing platform during periods

of bad weather and poor visibility [42] indicate that wind farms located near the coast or prominent

migration bottlenecks may pose a significant risk to migrating birds More recent evidence also

shows alternative crossing options for some passerine species including non‐stop crossings over the

Mediterranean Sea [43] This indicates that species‐specific migrations are not fixed either temporally

or spatially and individual route decisions are due to risk analysis of many parameters including

energy reserves weather conditions and genetic disposition [4445] Until large‐scale migration

routes across the Mediterranean Sea are better understood developers face large difficulties in wind

farm spatial planning in the region Obtaining this information is an essential task for potential OWF

developers in the Mediterranean

Figure 2 Main Mediterranean wetlands and overlapping OWF potential hotspot areas (adaptedfrom [41] 1 Ebro Delta 2 Camargue Delta 3 Po Delta 4 Amvrakikos Gulf 5 Prespa Basin6 Aliakmonas Delta 7 Evros Delta 8 Gediz Delta 9 Goumlksu Delta 10 Seyhan Delta 11 Nile Delta12 Gabegraves Delta 13 El Kala

High collision levels of migrating terrestrial birds at well-lit observing platform during periodsof bad weather and poor visibility [42] indicate that wind farms located near the coast or prominentmigration bottlenecks may pose a significant risk to migrating birds More recent evidence alsoshows alternative crossing options for some passerine species including non-stop crossings over theMediterranean Sea [43] This indicates that species-specific migrations are not fixed either temporallyor spatially and individual route decisions are due to risk analysis of many parameters includingenergy reserves weather conditions and genetic disposition [4445] Until large-scale migration routesacross the Mediterranean Sea are better understood developers face large difficulties in wind farmspatial planning in the region Obtaining this information is an essential task for potential OWFdevelopers in the Mediterranean

Aside from identifying crucial regions for migrating birds one of the most poorly understoodaspects about OWF effects on birds is avoidance behavior Turbine avoidance tactics employed bya species may apply to both resident seabirds and long-distance migrants however any changesto migratory routes are extremely difficult to monitor and may have large indirect effects [42]Avoidance behavior is possible at several scales which are typically classified into micro mesoand macro strategies Micro-avoidance is the behavioral response to actively avoid rotating bladesMeso-avoidance is classified as behavior whereby species that fly at rotor height within the wind

J Mar Sci Eng 2016 4 18 6 of 17

farm and avoid the whole rotor swept zone and macro-avoidance being the behavioral alteration ofa flight path due to the presence of a wind farm [46] Macro-avoidance behavior strategies have beenshown in some migrating individuals The common eider Somateria mollissima for example exhibitedavoidance behaviors of a wind turbine at a range of up to 500 m during the day [47] The long-termconsequences of employing avoidance techniques remain unclear Among other parameters realimpacts to population trends of migrating birds will be highly dependent on the specific life historiesof a species expenditure of avoidance strategies energy reserves and weather conditions duringmigratory periods

There are several possible measures to reduce the effects wind farms will have on Mediterraneanavian populations eg shutdown orders and changes to the phototaxis level of structures [4849]However preventative initiatives are much more effective ie ensuring planning and placementof OWFs are not in the vicinity of large population of species that have been identified as high riskwithin the Mediterranean The sensitive species suggested here due to collision or habitat vulnerabilityinclude the lesser black-backed gull the Northern gannet and the red- and black-throated divers whilethe endemic bird species and species whose populations are declining in recent decades (Shearwaters)are identified due to their conservation importance (Table 1) More understanding of the cumulativeeffects of all impacts at all potential development sites is needed Until then all future approaches inregard to OWF spatial planning in the Mediterranean should be of a cautionary nature

32 Potential Effects of Mediterranean Marine Mammals

Marine mammals are often high profile charismatic species and have the potential for highsocio-economic value in their natural habitats [50] It is therefore essential to understand the effectsOWFs will have on Mediterranean populations The Mediterranean Sea is home to both resident andvisiting marine mammals of which most are experiencing a decline in population trends with theexception of visiting humpback whales whose numbers have appeared to increase [1151] At a basinlevel total population numbers are difficult to assess with several species being classified as ldquodatadeficientrdquo by the IUCN red list [20] Nonetheless certain regions have been identified as importanthabitats for marine mammals Monitoring programs show a high percentage of fin whale sightingswithin the Ligurian Sea in comparison with other regions of the Mediterranean Sea [52] The AlboreanSea has been shown to be an important for long-finned pilot whale populations [53] and there is alsoevidence that due to the East-West basin migration of Sperm whales either the Strait of Sicily or theStrait of Messina are critical areas which enable migration [54]

In regard to OWF development several resident marine mammals frequently use the coastalmarine environment earmarked for potential developments including the critically endangeredMediterranean monk seal the common Bottlenose dolphin and visiting Humpback whales [515556]When assessing the combined species density of the resident marine mammals the Gulf of Lion OWFhotspot displays the highest densities of resident marine mammals and as such can be considered asthe most sensitive in regard to OWF development The Gulfs of Hammamet and Gabegraves the Gulf ofSidra and the Nile Delta hotspots appear to support low populations of resident marine mammals(Figure 3)

The distribution of specific species of marine mammals is also of interest to developers This isparticularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently usesthe coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the coast ofTrieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include the thecoast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These regionswill require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise andin particular pile driving during construction has been identified as the biggest impact to marinemammals [58] Increased motorized vessel shipping during the operational phase of wind farms alsoincreases noise levels to the area and so is also identified as an impact however this is not at a level

J Mar Sci Eng 2016 4 18 7 of 17

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the speciespile driven construction has the ability to produce hearing impairment although for most specieshearing reactions are as yet undetermined [60]J Mar Sci Eng 2016 4 18 7 of 17

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Image

adapted from Coll et al [11])

The distribution of specific species of marine mammals is also of interest to developers This is

particularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently

uses the coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the

coast of Trieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include

the the coast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These

regions will require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise and in

particular pile driving during construction has been identified as the biggest impact to marine

mammals [58] Increased motorized vessel shipping during the operational phase of wind farms also

increases noise levels to the area and so is also identified as an impact however this is not at a level

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the species

pile driven construction has the ability to produce hearing impairment although for most species

hearing reactions are as yet undetermined [60]

A study measuring the propagation of sound during the construction phase of an offshore site

in the NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range

of the site and behavior disturbances up to 50 km away [61] With the use of T‐POD porpoise

detectors acoustic monitoring during the construction and into the operational phase of the Nysted

OWF indicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a

reduction in the level of echolocation signals produced by the porpoises [62] A long‐term study (10

years) at the same wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measured

significantly higher acoustic activity inside the farm in comparison with a control site [64] and this

trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggested an

increase in habitat utilization at two operational wind farms (Alpha Ventus and Sheringham Shoal)

[65] The repeated grid‐like movements indicated for the first time successful foraging behavior by

an apex predator within an OWF The apparent differences between probable habitat uses may be

due to local‐scale ecological differences local population habituation of wind farms or differences in

construction type of wind farms [64] Due to critical population levels in the Mediterranean the

observed increases in seal foraging behavior around wind farms may not be relevant to the

Mediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi‐enclosed Mediterranean

also suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In

general noise from wind farms is influenced by water depth wind speed turbine type wind farm

size and substratum type [67] due to the high levels of existing background noise from maritime

traffic in the Mediterranean risks having a cumulative effect in masking communicative abilities of

marine species [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots

of the Gulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels

within the area (up to 140 m vessels∙kmminus2∙dayminus1) thus high levels of background noise can be expected

in these regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levels

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Imageadapted from Coll et al [11])

A study measuring the propagation of sound during the construction phase of an offshore site inthe NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range ofthe site and behavior disturbances up to 50 km away [61] With the use of T-POD porpoise detectorsacoustic monitoring during the construction and into the operational phase of the Nysted OWFindicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a reductionin the level of echolocation signals produced by the porpoises [62] A long-term study (10 years) at thesame wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measuredsignificantly higher acoustic activity inside the farm in comparison with a control site [64] andthis trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggestedan increase in habitat utilization at two operational wind farms (Alpha Ventus and SheringhamShoal) [65] The repeated grid-like movements indicated for the first time successful foraging behaviorby an apex predator within an OWF The apparent differences between probable habitat uses may bedue to local-scale ecological differences local population habituation of wind farms or differencesin construction type of wind farms [64] Due to critical population levels in the Mediterraneanthe observed increases in seal foraging behavior around wind farms may not be relevant to theMediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi-enclosed Mediterraneanalso suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In generalnoise from wind farms is influenced by water depth wind speed turbine type wind farm size andsubstratum type [67] due to the high levels of existing background noise from maritime traffic inthe Mediterranean risks having a cumulative effect in masking communicative abilities of marinespecies [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots of theGulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels withinthe area (up to 140 m vesselsuml kmacute2uml dayacute1) thus high levels of background noise can be expected inthese regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levelsof background noise stress The use of underwater noise propagation models by policy makers willbe required to understand the combined influence of OWF construction operation and maintenanceshipping with current levels of background noise at site-specific locations

J Mar Sci Eng 2016 4 18 8 of 17

J Mar Sci Eng 2016 4 18 8 of 17

of background noise stress The use of underwater noise propagation models by policy makers will

be required to understand the combined influence of OWF construction operation and maintenance

shipping with current levels of background noise at site‐specific locations

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vessel

monitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing‐related activities particularly artisanal

fishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean

8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline of

Mediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro‐magnetic

fields and novel habitat gain Recent studies have shown that the noise generated by pile driving

during the construction phase of OWF farms can generate acute stress responses in juvenile fish

species Although the responses were recorded as acute it is possible that repeated and prolonged

exposure in the wild may lead to a decrease in fitness [72] During the operational stages of OWFs

evidence indicates fish permanently avoid wind turbines only at a range of up to 4 m under high

wind speeds (13 msminus1) and that their ability to communicate and utilize orientation signals is masked

[67] Increased background noise and seabed vibration from operational OWFs and associated marine

traffic will also influence fish detection distances [7374] (Figure 4) Greater numbers of experimental

studies on individual fish species are needed before we can fully comprehend the impact of

anthropogenic noise on fish [75]

Electromagnetic fields occur around intra‐turbine array‐to‐transformer and transformer‐to‐

shore cables The electro‐sensitivity of many marine species is unknown and there is a dearth of peer‐

reviewed information regarding the effects of electro‐magnetic fields Elasmobranchs are thought to

be especially sensitive due to their electro‐sensory organs [76] Several shark and ray species react to

wind farm cables [77] but whether this has any affect at the population level is unknown Magnetic

fields could influence geomagnetic patterns used by some migratory marine species for navigation

[78] and reports also show that electro‐magnetic fields from OWFs may affect fish migration Gill et

al [79] identified eight migratory fish species sensitive to electromagnetic fields including the

European eel Anguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus

albacares Limited in situ data are available about the actual effects on fish which rely on magnetic

fields for migration however several studies in the Baltic Sea have indicated that the swimming

speed of European eels is reduced in the vicinity of underwater electric cables [7880] However due

to the limited availability of empirical studies it is difficult to theorize the extent of the impacts that

electro‐magnetic fields have on Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition of novel

vertical habitat to an area previously void of hard substratum Numerous studies have found greater

abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhua

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vesselmonitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing-related activities particularly artisanalfishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline ofMediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro-magnetic fieldsand novel habitat gain Recent studies have shown that the noise generated by pile driving during theconstruction phase of OWF farms can generate acute stress responses in juvenile fish species Althoughthe responses were recorded as acute it is possible that repeated and prolonged exposure in the wildmay lead to a decrease in fitness [72] During the operational stages of OWFs evidence indicates fishpermanently avoid wind turbines only at a range of up to 4 m under high wind speeds (13 msacute1) andthat their ability to communicate and utilize orientation signals is masked [67] Increased backgroundnoise and seabed vibration from operational OWFs and associated marine traffic will also influencefish detection distances [7374] (Figure 4) Greater numbers of experimental studies on individual fishspecies are needed before we can fully comprehend the impact of anthropogenic noise on fish [75]

Electromagnetic fields occur around intra-turbine array-to-transformer and transformer-to-shorecables The electro-sensitivity of many marine species is unknown and there is a dearth ofpeer-reviewed information regarding the effects of electro-magnetic fields Elasmobranchs are thoughtto be especially sensitive due to their electro-sensory organs [76] Several shark and ray species reactto wind farm cables [77] but whether this has any affect at the population level is unknown Magneticfields could influence geomagnetic patterns used by some migratory marine species for navigation [78]and reports also show that electro-magnetic fields from OWFs may affect fish migration Gill et al [79]identified eight migratory fish species sensitive to electromagnetic fields including the European eelAnguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus albacares Limitedin situ data are available about the actual effects on fish which rely on magnetic fields for migrationhowever several studies in the Baltic Sea have indicated that the swimming speed of European eels isreduced in the vicinity of underwater electric cables [7880] However due to the limited availabilityof empirical studies it is difficult to theorize the extent of the impacts that electro-magnetic fields haveon Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition ofnovel vertical habitat to an area previously void of hard substratum Numerous studies have foundgreater abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhuapouting Trisopterus luscus and several species of gobies [81ndash83] Currently most empirically measuredeffects due to operational wind turbines are temporally limited and not at the scale of OWFs [60]Several studies have implied that the new habitat provides increased foraging for both primaryand secondary food resources and protection grounds from currents [84] There is much discussion

J Mar Sci Eng 2016 4 18 9 of 17

between ecologists over whether changes in species biomass will be due to attraction or production [85]Stomach content analysis and energy profiling have shown that OWFs are suitable feeding groundsfor both Atlantic cod and pouting species [8687] indicating that there is extra biomass available at thesites Juvenile recruitment of Atlantic cod has also been observed at wind farms in the Belgium partof the North Sea [87] Changes in prey densities may also be masked by predation rates [6588] andwill potentially strengthen predator avoidance behaviors like diel migration further complicating therelationship between attraction-production dynamics [77] While the mechanics of fish abundanceat OWFs is not yet fully understood and requires additional analysis it is becoming increasinglyobvious that any ecological benefits will only be attained if fishing practices are banned within thewind farms [89]

For Mediterranean fish species it is difficult to state the effects based on the findings of NorthernEuropean studies as there is a limited availability of information and the majority of existingmonitoring programs focus on species that are not generally present in Mediterranean waters egAtlantic cod [828588] That being said there is evidence that suggests a yield increase of fishpopulations at wind farms as opposed to the simple attraction model previously hypothesized [8586]This is of particular importance for the Mediterranean as levels of fishing are unsustainable and mostfish stocks are in decline [71] The possibility for creating de facto marine protected areas (MPAs) due tofishing restrictions imposed within OWFs is an interesting aspect in the developments of OWFs in theMediterranean Sea It is clear that well protected MPAs in the Mediterranean result in significantlyhigher biomass than those with no or minimal protection [90] although many Mediterranean MPAslack adequate protection [91] Enforcement of fishing restrictions in Mediterranean MPAs is a difficultissue but the benefit associated with designating an area within a series of fixed structures is thatfishing regulations may be easier to enforce Benthic fishermen are less willing to drag their trawlinggear within turbines as they risk entanglement and there is a potential to monitor fishing activity ofstatic and recreational fishermen by using fixed cameras It is worth noting however that displacementof fishing effort is a serious concern for the management of reduced fishing effort regions [92]The production of sound by many fish species for communication during spawning periods means itis also essential for policy makers to identify fish spawning grounds during environmental impactassessments with the aim of restricting OWF construction in these noise-sensitive areas [93]

34 Potential Effects of Mediterranean Benthic Communities

The Mediterranean harbors many important benthic habitats including vermetid reefs coralligenicconcentrations shallow sublittoral rock seamounts deep-sea coral reefs and abyssal plains [9495]The shallow sub-littoral sediment is a particularly valuable habitat for the Mediterranean benthos as itis the preferred habitat of the endemic seagrass Posidonia oceanica listed as a priority natural habitatunder Annex 1 of the EC Habitats Directive (243EEC on the Conservation of Natural Habitatsand of Wild Fauna and Flora) due to its endemism high productivity and provision of ecosystemservices [9697] Favorable substrate conditions for OWF construction throughout Europe is typicallysoft sediment areas and the piling and drilling of foundations and monopile jackets constitutes the mostdirect impact to the marine environment As they favor similar habitats required for the constructionof OWFs Posidonia beds are at risk from direct physical destruction sedimentation and changes inhydrographic regimes Conversely construction may prevent local trawling and therefore decrease theamount of destructive fishing methods that typically reduces Posidonia coverage [98] Any plans forOWFs in the Mediterranean Sea will have to be carefully designed around the distribution of Posidoniato ensure the correct conservation practices for this endemic priority species

Other impacts to soft sediment communities from pre-construction states include changes inregional current regimes causing shifts in macro-benthic assemblages on a localized scale [99100]Studies have shown negative correlations between distance from turbines and grain sizes in the vicinityof turbines (measured from a distance from turbine of 15 m to 200 m) in the Belgian part of the NorthSea which were also positively correlated with increases in organic matter and a shift in species

J Mar Sci Eng 2016 4 18 10 of 17

assemblages The closer to the turbine the soft sediment community samples were taken the greaterthe increase in macrobenthic density and diversity [99]

Although changes in soft-sediment in-fauna are likely to be associated with wind farmconstruction the most direct affect is the addition of hard substratum to the environment Ecosystemshifts occur from changes in the existing soft sediment shifts and the addition of hard substratum ina habitat previously void of available settlement substratum Recruitment and colonization of novelartificial habitats provided by turbine foundations increases the structural complexity and productivityof an environment previously low in in-fauna diversity and density [101ndash110]

Research at an offshore research platform in the German Bight indicated that 35 times moremacro-zoobenthos biomass was associated with the additional hard substratum than the equivalentarea of soft benthic sediment [81] The increase in macro-zoobenthos biomass may appearbeneficial in regard to productivity yet in many cases species assemblages associated with artificialstructures differ from the environment replaced and show lower levels of diversity than natural rockequivalents [81110] Long-term effects of ecosystem shifts are unknown and species assemblagesare influenced by many parameters including material and texture of offshore structures larvalsupply oceanographic conditions temperature salinity and water depth [111] The number ofdefining parameters involved in influencing the spatial and temporal colonization of offshore artificialstructures highlights the need for extensive area-specific research and long-tem in situ experiments tofully understand regional implications of OWFs

With regard to the Mediterranean the limited investigative work into epibenthic colonization hasfocused on concrete artificial reefs [112ndash114] or rock anthropogenic structures [115116] Most studiesareas focus on the Northwestern region of the Mediterranean with the exception of two studies inTurkey and Israel [117118] Only two studies have investigated an offshore steel structure in theMediterranean [117118] Dominating species of epibenthic assemblages varied depending on thelocation and duration of monitoring program which ranged from 11 months to 20 years Most studiescited the initial establishment of Hydozoa Bryozoa and Serpulidae [112117ndash120] In several studiesinitial colonization was followed with the establishment and dominance of the commercially farmedMytilus galloprovincialis [112115119120] However the establishment of mussel beds on artificialstructures in the Mediterranean may be highly localized as several artificial structures showed no suchdominance [117121ndash123] or highly variable results [124] The only long-term data set on a concreteartificial reef (20 years) reported five distinct phases of species assemblage dominance of pioneerspecies mussel dominance mussel regression mussels absence and finally dominance of bryozoanbio-constructions [125] Differences in the material used for offshore structures may have a significanteffect on climax community composition the two offshore steel study sites in the Mediterraneanoffshore steel structures were both dominated by bivalves after 52 and 70 months [119121]

The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonizationof artificial substrata in the Mediterranean by alien species [122127] mean that wind farms may also actas benthic ldquostepping stonesrdquo that facilitate range extension of alien species within the Mediterraneanmarine environment which in turn may potentially reduce the biodiversity of the basin [111128]Due to the apparent locality factor of benthic colonization communites small-scale pilot studies areessential for understanding whether windfarms will proliferate alien species at potential wind farmlocations The use of before-after control-impact studies by policy makers is strongly recommended

35 Potential Effects of Mediterranean Planktonic Communities

The oxygen rich oligotrophic waters of the semi-enclosed Mediterranean produce a lownutrient availability that is however generally intensified along both a west-east and north-southdirection [129] There is nevertheless a high spatial heterogeneity in the distribution of planktonthroughout the Mediterranean Sea due to complex hydrodynamic circulation patterns formingmultiple gyres and upwelling systems [130] Most marine invertebrate and fish species havea planktonic larval stage therefore it is crucial to understand any effects OWFs may have on planktonic

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 3 of 17

Mediterranean Sea Here we consider the potential effects on birds marine mammals fish benthosand plankton throughout the Mediterranean and where available the possible impacts of OWFswithin the specific hotspot regions

J Mar Sci Eng 2016 4 18 3 of 17

and plankton throughout the Mediterranean and where available the possible impacts of OWFs

within the specific hotspot regions

Figure 1 Locations which satisfy offshore wind development requirements of 20ndash50 m depth and an

annual wind speed gt5 msminus1 at a height of 80 m above sea level A Gulf of Lion B North Adriatic Sea

C Gulfs of Hammamet and Gabegraves D Gulf of Sidra E Nile Delta

31 Potential Effects of Mediterranean Offshore Wind Farms on Birds

Wind farms affect resident and migrating birds through avoidance behaviors habitat

displacement and collision mortality but such impacts are difficult to monitor offshore [19] Seabirds

that use the marine environment for foraging or resting may be displaced by OWFs [20] The

Mediterranean has a low diversity of seabirds but these species tend to be long‐lived with low

fecundity traits that often make species vulnerable to abrupt environmental change [1120] (Table 1)

Fortunately most Mediterranean marine birds are listed as ldquoleast concernrdquo on the IUCN red list

although the Audouinʹs gull is listed as ldquonear threatenedrdquo the Yelkouan shearwater as ldquovulnerablerdquo

and the Balearic shearwater as ldquocritically endangeredrdquo [21] All 16 Mediterranean countries have

made commitments to protect these species at a national level [22] With the exception of shearwaters

[23] Mediterranean seabird populations appear to be increasing particularly the yellow‐legged gull

[112425] These increases have been attributed to fish discards and improvements in coastal

conservation [26ndash28] but changes to fishery discard practices following the reform of the Common

Fisheries Policy may reverse this [29]

Studies of Northern European seabird populations have developed vulnerability indices to

indicate seabirds likely to be affected by the presence of OWFs [30ndash32] Using parameters that are

heavily weighted on the risks of collision mortality (flight altitude flight manoeuvrability percentage

of flight time nocturnal flight altitude disturbance by wind farm structures ship and helicopter

traffic and habitat specialization) the NorthBaltic Sea‐based studies assessed 18 of the 29

Mediterranean seabirds Notable exclusions to the list are the endemic species of the Mediterranean

which pose a greater conservation risk due to their small population sizes [33] Garthe and Huumlppop

[13] identify the Black and Red‐throated diver the Sandwich tern and the great Cormorant as the

most sensitive of the Mediterranean seabirds within their index and rated the Black‐legged kittiwake

and the Black‐headed gull as the least sensitive when all parameters were combined Advancing this

approach Furness et al [31] separated the hazards due to collision risk and habitat displacement

They identified the lesser black‐backed gull and the Northern gannet as marine species sensitive to

collision risk and both the red and black‐necked divers as most susceptible to long‐term habitat

displacement These approaches lack any evaluation of species‐specific OWF avoidance behavior and

thus have large caveats attached to their findings The approach of identifying at risk species via

vulnerability indices is useful for the planning stages of OWFs however it does not determine if

construction will have a detectable change in seabird population trends Focus should preferably be

given to understanding any direct effects OWFs will have on foraging success eg diving behavior

Figure 1 Locations which satisfy offshore wind development requirements of 20ndash50 m depth andan annual wind speed gt5 msacute1 at a height of 80 m above sea level A Gulf of Lion B North AdriaticSea C Gulfs of Hammamet and Gabegraves D Gulf of Sidra E Nile Delta

31 Potential Effects of Mediterranean Offshore Wind Farms on Birds

Wind farms affect resident and migrating birds through avoidance behaviors habitatdisplacement and collision mortality but such impacts are difficult to monitor offshore [19]Seabirds that use the marine environment for foraging or resting may be displaced by OWFs [20]The Mediterranean has a low diversity of seabirds but these species tend to be long-lived withlow fecundity traits that often make species vulnerable to abrupt environmental change [1120](Table 1) Fortunately most Mediterranean marine birds are listed as ldquoleast concernrdquo on the IUCNred list although the Audouins gull is listed as ldquonear threatenedrdquo the Yelkouan shearwater asldquovulnerablerdquo and the Balearic shearwater as ldquocritically endangeredrdquo [21] All 16 Mediterraneancountries have made commitments to protect these species at a national level [22] With the exceptionof shearwaters [23] Mediterranean seabird populations appear to be increasing particularly theyellow-legged gull [112425] These increases have been attributed to fish discards and improvementsin coastal conservation [26ndash28] but changes to fishery discard practices following the reform of theCommon Fisheries Policy may reverse this [29]

Studies of Northern European seabird populations have developed vulnerability indices toindicate seabirds likely to be affected by the presence of OWFs [30ndash32] Using parameters that areheavily weighted on the risks of collision mortality (flight altitude flight manoeuvrability percentageof flight time nocturnal flight altitude disturbance by wind farm structures ship and helicopter trafficand habitat specialization) the NorthBaltic Sea-based studies assessed 18 of the 29 Mediterraneanseabirds Notable exclusions to the list are the endemic species of the Mediterranean which posea greater conservation risk due to their small population sizes [33] Garthe and Huumlppop [13] identifythe Black and Red-throated diver the Sandwich tern and the great Cormorant as the most sensitiveof the Mediterranean seabirds within their index and rated the Black-legged kittiwake and theBlack-headed gull as the least sensitive when all parameters were combined Advancing this approachFurness et al [31] separated the hazards due to collision risk and habitat displacement They identifiedthe lesser black-backed gull and the Northern gannet as marine species sensitive to collision risk andboth the red and black-necked divers as most susceptible to long-term habitat displacement Theseapproaches lack any evaluation of species-specific OWF avoidance behavior and thus have largecaveats attached to their findings The approach of identifying at risk species via vulnerability indicesis useful for the planning stages of OWFs however it does not determine if construction will have

J Mar Sci Eng 2016 4 18 4 of 17

a detectable change in seabird population trends Focus should preferably be given to understandingany direct effects OWFs will have on foraging success eg diving behavior and prey characteristicswhich in turn will impact reproductive success juvenile survival and population trends [20]

Table 1 Mediterranean seabird sensitivity assessments highlighting most and least vulnerable speciesaccording to index Y = Yes N = No Red = 10 most vulnerable Mediterranean species within indexBlue = 10 least vulnerable species within index ldquo-rdquo = Index not applied

Common Name Species EndemicListed under

BarcelonaConvention

Wind FarmSensitivityIndex [13]

VulnerabilityIndex forCollision

Impacts [30]

VulnerabilityIndex for

DisturbanceImpacts [30]

Coryrsquos Shearwater(Mediterranean)

Calonectris diomedeadiomedea Y Y - - -

YelkouanShearwater

(Mediterranean)Puffinus yelkouan Y N - - -

Balearic Shearwater Puffinusmauretanicus Y N - - -

European Shag(Mediterranean)

Phalacrocoraxaristotelis desmarestii Y Y - 150 14

Great Comorant Phalacrocorax carbo N N 233 - -

Pygmy Comorant Phalacrocoraxpygmeus N N - - -

Audouinrsquos gull Larus audouinii N Y - - -

Little Gull Hydrcoleus minutus N N 128 - -

Lesser black-backedgull Larus fuscus N N 138 960 3

Slender billed gull Larus genei N Y - - -

Mediterranean gull Larus melanocephalus N Y - - -

Black-headed gull Larus ridibundus N N 75 - -

Caspian gull Larus cachinnans N N - - -

Black leggedkittiwake Rissa tridactyla N N 75 -

Yellow legged gull Larus michahellis N N - - -

Great skua Catharacta skua N N - 320 3

Caspian tern Hydroprogne caspia N N - - -

Common tern Sterna hirundo N N 150 229 8

Little tern Sterna albifrons N N - 212 10

Sandwich tern Sterna sandvicensis N N 250 245 9

Lesser-crested tern Thalasseusbengalensis N N - -

Razorbill Alca torda N N 158 32 14

Atlantic puffin Fratercula arctica N N 150 27 10

European Stormpetrel

Hydrobates pelagicmelitensis Y Y - 91 2

Northern gannet Morus bassanus N N - - -

Osprey Pandion haliaetus N Y - - -

Eleanorersquos falcon Falco eleonorae N Y - - -

Red throated diver Gavia stellata N N 433 213 32

Black throated diver Gavia arctica N N 403 240 32

Great crested grebe Podicep scristatus N N 193 84 8

Red-necked grebe Podiceps grisegena N N 187 - -

Eared grebe Podiceps nigricollis N N - - -

J Mar Sci Eng 2016 4 18 5 of 17

Threats to Mediterranean bird populations are also directed towards migratory speciesWorldwide migratory species are declining in greater numbers than resident populations [34] and theMediterranean basin is a major transit route for Saharan-Eurasian migration as evidenced by both theMediterranean-Black Sea flyway and the Adriatic flyway [3536] Many long-distance bird migrantseg raptors and storks rely on land lift via thermal upwelling for long-distance flight [3738] andavoid broad fronts such as the Mediterranean Sea and the Saharan desert [37] creating bottlenecksat narrow passages of the Mediterranean Sea including Gibraltar the Straits of Sicily Messina (Italy)and the Belen pass (Turkey) [39] Wetlands around the Mediterranean provide suitable stopoversites for long-distance migrants to feed rest and molt [40] Some of the main wetlands around theMediterranean are located within close proximity of potential OWF hotspots particularly the Po Deltain the Northern Adriatic Sea the Nile Delta the Gabegraves Delta and the Camargue Delta in the Gulf ofLion (Figure 2) Due to the bathymetry of the Mediterranean and the steep continental slope of mostcoastlines deltas provide feasible sites for wind farm constructions High densities of avian habitatuse in these regions means that OWF resource overlap will be a key factor in Mediterranean marinespatial planning in regard to OWFs

J Mar Sci Eng 2016 4 18 5 of 17

Black throated

diver Gavia arctica N N 403 240 32

Great crested

grebe

Podicep

scristatus N N 193 84 8

Red‐necked grebe Podiceps

grisegena N N 187 ‐ ‐

Eared grebe Podiceps

nigricollis N N ‐ ‐ ‐

Threats to Mediterranean bird populations are also directed towards migratory species

Worldwide migratory species are declining in greater numbers than resident populations [34] and

the Mediterranean basin is a major transit route for Saharan‐Eurasian migration as evidenced by

both the Mediterranean‐Black Sea flyway and the Adriatic flyway [3536] Many long‐distance bird

migrants eg raptors and storks rely on land lift via thermal upwelling for long‐distance flight

[3738] and avoid broad fronts such as the Mediterranean Sea and the Saharan desert [37] creating

bottlenecks at narrow passages of the Mediterranean Sea including Gibraltar the Straits of Sicily

Messina (Italy) and the Belen pass (Turkey) [39] Wetlands around the Mediterranean provide

suitable stopover sites for long‐distance migrants to feed rest and molt [40] Some of the main

wetlands around the Mediterranean are located within close proximity of potential OWF hotspots

particularly the Po Delta in the Northern Adriatic Sea the Nile Delta the Gabegraves Delta and the

Camargue Delta in the Gulf of Lion (Figure 2) Due to the bathymetry of the Mediterranean and the

steep continental slope of most coastlines deltas provide feasible sites for wind farm constructions

High densities of avian habitat use in these regions means that OWF resource overlap will be a key

factor in Mediterranean marine spatial planning in regard to OWFs

Figure 2 Main Mediterranean wetlands and overlapping OWF potential hotspot areas (adapted from

[41] 1 Ebro Delta 2 Camargue Delta 3 Po Delta 4 Amvrakikos Gulf 5 Prespa Basin 6 Aliakmonas

Delta 7 Evros Delta 8 Gediz Delta 9 Gӧksu Delta 10 Seyhan Delta 11 Nile Delta 12 Gabegraves Delta

13 El Kala

High collision levels of migrating terrestrial birds at well‐lit observing platform during periods

of bad weather and poor visibility [42] indicate that wind farms located near the coast or prominent

migration bottlenecks may pose a significant risk to migrating birds More recent evidence also

shows alternative crossing options for some passerine species including non‐stop crossings over the

Mediterranean Sea [43] This indicates that species‐specific migrations are not fixed either temporally

or spatially and individual route decisions are due to risk analysis of many parameters including

energy reserves weather conditions and genetic disposition [4445] Until large‐scale migration

routes across the Mediterranean Sea are better understood developers face large difficulties in wind

farm spatial planning in the region Obtaining this information is an essential task for potential OWF

developers in the Mediterranean

Figure 2 Main Mediterranean wetlands and overlapping OWF potential hotspot areas (adaptedfrom [41] 1 Ebro Delta 2 Camargue Delta 3 Po Delta 4 Amvrakikos Gulf 5 Prespa Basin6 Aliakmonas Delta 7 Evros Delta 8 Gediz Delta 9 Goumlksu Delta 10 Seyhan Delta 11 Nile Delta12 Gabegraves Delta 13 El Kala

High collision levels of migrating terrestrial birds at well-lit observing platform during periodsof bad weather and poor visibility [42] indicate that wind farms located near the coast or prominentmigration bottlenecks may pose a significant risk to migrating birds More recent evidence alsoshows alternative crossing options for some passerine species including non-stop crossings over theMediterranean Sea [43] This indicates that species-specific migrations are not fixed either temporallyor spatially and individual route decisions are due to risk analysis of many parameters includingenergy reserves weather conditions and genetic disposition [4445] Until large-scale migration routesacross the Mediterranean Sea are better understood developers face large difficulties in wind farmspatial planning in the region Obtaining this information is an essential task for potential OWFdevelopers in the Mediterranean

Aside from identifying crucial regions for migrating birds one of the most poorly understoodaspects about OWF effects on birds is avoidance behavior Turbine avoidance tactics employed bya species may apply to both resident seabirds and long-distance migrants however any changesto migratory routes are extremely difficult to monitor and may have large indirect effects [42]Avoidance behavior is possible at several scales which are typically classified into micro mesoand macro strategies Micro-avoidance is the behavioral response to actively avoid rotating bladesMeso-avoidance is classified as behavior whereby species that fly at rotor height within the wind

J Mar Sci Eng 2016 4 18 6 of 17

farm and avoid the whole rotor swept zone and macro-avoidance being the behavioral alteration ofa flight path due to the presence of a wind farm [46] Macro-avoidance behavior strategies have beenshown in some migrating individuals The common eider Somateria mollissima for example exhibitedavoidance behaviors of a wind turbine at a range of up to 500 m during the day [47] The long-termconsequences of employing avoidance techniques remain unclear Among other parameters realimpacts to population trends of migrating birds will be highly dependent on the specific life historiesof a species expenditure of avoidance strategies energy reserves and weather conditions duringmigratory periods

There are several possible measures to reduce the effects wind farms will have on Mediterraneanavian populations eg shutdown orders and changes to the phototaxis level of structures [4849]However preventative initiatives are much more effective ie ensuring planning and placementof OWFs are not in the vicinity of large population of species that have been identified as high riskwithin the Mediterranean The sensitive species suggested here due to collision or habitat vulnerabilityinclude the lesser black-backed gull the Northern gannet and the red- and black-throated divers whilethe endemic bird species and species whose populations are declining in recent decades (Shearwaters)are identified due to their conservation importance (Table 1) More understanding of the cumulativeeffects of all impacts at all potential development sites is needed Until then all future approaches inregard to OWF spatial planning in the Mediterranean should be of a cautionary nature

32 Potential Effects of Mediterranean Marine Mammals

Marine mammals are often high profile charismatic species and have the potential for highsocio-economic value in their natural habitats [50] It is therefore essential to understand the effectsOWFs will have on Mediterranean populations The Mediterranean Sea is home to both resident andvisiting marine mammals of which most are experiencing a decline in population trends with theexception of visiting humpback whales whose numbers have appeared to increase [1151] At a basinlevel total population numbers are difficult to assess with several species being classified as ldquodatadeficientrdquo by the IUCN red list [20] Nonetheless certain regions have been identified as importanthabitats for marine mammals Monitoring programs show a high percentage of fin whale sightingswithin the Ligurian Sea in comparison with other regions of the Mediterranean Sea [52] The AlboreanSea has been shown to be an important for long-finned pilot whale populations [53] and there is alsoevidence that due to the East-West basin migration of Sperm whales either the Strait of Sicily or theStrait of Messina are critical areas which enable migration [54]

In regard to OWF development several resident marine mammals frequently use the coastalmarine environment earmarked for potential developments including the critically endangeredMediterranean monk seal the common Bottlenose dolphin and visiting Humpback whales [515556]When assessing the combined species density of the resident marine mammals the Gulf of Lion OWFhotspot displays the highest densities of resident marine mammals and as such can be considered asthe most sensitive in regard to OWF development The Gulfs of Hammamet and Gabegraves the Gulf ofSidra and the Nile Delta hotspots appear to support low populations of resident marine mammals(Figure 3)

The distribution of specific species of marine mammals is also of interest to developers This isparticularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently usesthe coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the coast ofTrieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include the thecoast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These regionswill require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise andin particular pile driving during construction has been identified as the biggest impact to marinemammals [58] Increased motorized vessel shipping during the operational phase of wind farms alsoincreases noise levels to the area and so is also identified as an impact however this is not at a level

J Mar Sci Eng 2016 4 18 7 of 17

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the speciespile driven construction has the ability to produce hearing impairment although for most specieshearing reactions are as yet undetermined [60]J Mar Sci Eng 2016 4 18 7 of 17

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Image

adapted from Coll et al [11])

The distribution of specific species of marine mammals is also of interest to developers This is

particularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently

uses the coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the

coast of Trieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include

the the coast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These

regions will require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise and in

particular pile driving during construction has been identified as the biggest impact to marine

mammals [58] Increased motorized vessel shipping during the operational phase of wind farms also

increases noise levels to the area and so is also identified as an impact however this is not at a level

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the species

pile driven construction has the ability to produce hearing impairment although for most species

hearing reactions are as yet undetermined [60]

A study measuring the propagation of sound during the construction phase of an offshore site

in the NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range

of the site and behavior disturbances up to 50 km away [61] With the use of T‐POD porpoise

detectors acoustic monitoring during the construction and into the operational phase of the Nysted

OWF indicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a

reduction in the level of echolocation signals produced by the porpoises [62] A long‐term study (10

years) at the same wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measured

significantly higher acoustic activity inside the farm in comparison with a control site [64] and this

trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggested an

increase in habitat utilization at two operational wind farms (Alpha Ventus and Sheringham Shoal)

[65] The repeated grid‐like movements indicated for the first time successful foraging behavior by

an apex predator within an OWF The apparent differences between probable habitat uses may be

due to local‐scale ecological differences local population habituation of wind farms or differences in

construction type of wind farms [64] Due to critical population levels in the Mediterranean the

observed increases in seal foraging behavior around wind farms may not be relevant to the

Mediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi‐enclosed Mediterranean

also suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In

general noise from wind farms is influenced by water depth wind speed turbine type wind farm

size and substratum type [67] due to the high levels of existing background noise from maritime

traffic in the Mediterranean risks having a cumulative effect in masking communicative abilities of

marine species [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots

of the Gulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels

within the area (up to 140 m vessels∙kmminus2∙dayminus1) thus high levels of background noise can be expected

in these regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levels

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Imageadapted from Coll et al [11])

A study measuring the propagation of sound during the construction phase of an offshore site inthe NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range ofthe site and behavior disturbances up to 50 km away [61] With the use of T-POD porpoise detectorsacoustic monitoring during the construction and into the operational phase of the Nysted OWFindicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a reductionin the level of echolocation signals produced by the porpoises [62] A long-term study (10 years) at thesame wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measuredsignificantly higher acoustic activity inside the farm in comparison with a control site [64] andthis trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggestedan increase in habitat utilization at two operational wind farms (Alpha Ventus and SheringhamShoal) [65] The repeated grid-like movements indicated for the first time successful foraging behaviorby an apex predator within an OWF The apparent differences between probable habitat uses may bedue to local-scale ecological differences local population habituation of wind farms or differencesin construction type of wind farms [64] Due to critical population levels in the Mediterraneanthe observed increases in seal foraging behavior around wind farms may not be relevant to theMediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi-enclosed Mediterraneanalso suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In generalnoise from wind farms is influenced by water depth wind speed turbine type wind farm size andsubstratum type [67] due to the high levels of existing background noise from maritime traffic inthe Mediterranean risks having a cumulative effect in masking communicative abilities of marinespecies [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots of theGulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels withinthe area (up to 140 m vesselsuml kmacute2uml dayacute1) thus high levels of background noise can be expected inthese regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levelsof background noise stress The use of underwater noise propagation models by policy makers willbe required to understand the combined influence of OWF construction operation and maintenanceshipping with current levels of background noise at site-specific locations

J Mar Sci Eng 2016 4 18 8 of 17

J Mar Sci Eng 2016 4 18 8 of 17

of background noise stress The use of underwater noise propagation models by policy makers will

be required to understand the combined influence of OWF construction operation and maintenance

shipping with current levels of background noise at site‐specific locations

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vessel

monitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing‐related activities particularly artisanal

fishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean

8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline of

Mediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro‐magnetic

fields and novel habitat gain Recent studies have shown that the noise generated by pile driving

during the construction phase of OWF farms can generate acute stress responses in juvenile fish

species Although the responses were recorded as acute it is possible that repeated and prolonged

exposure in the wild may lead to a decrease in fitness [72] During the operational stages of OWFs

evidence indicates fish permanently avoid wind turbines only at a range of up to 4 m under high

wind speeds (13 msminus1) and that their ability to communicate and utilize orientation signals is masked

[67] Increased background noise and seabed vibration from operational OWFs and associated marine

traffic will also influence fish detection distances [7374] (Figure 4) Greater numbers of experimental

studies on individual fish species are needed before we can fully comprehend the impact of

anthropogenic noise on fish [75]

Electromagnetic fields occur around intra‐turbine array‐to‐transformer and transformer‐to‐

shore cables The electro‐sensitivity of many marine species is unknown and there is a dearth of peer‐

reviewed information regarding the effects of electro‐magnetic fields Elasmobranchs are thought to

be especially sensitive due to their electro‐sensory organs [76] Several shark and ray species react to

wind farm cables [77] but whether this has any affect at the population level is unknown Magnetic

fields could influence geomagnetic patterns used by some migratory marine species for navigation

[78] and reports also show that electro‐magnetic fields from OWFs may affect fish migration Gill et

al [79] identified eight migratory fish species sensitive to electromagnetic fields including the

European eel Anguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus

albacares Limited in situ data are available about the actual effects on fish which rely on magnetic

fields for migration however several studies in the Baltic Sea have indicated that the swimming

speed of European eels is reduced in the vicinity of underwater electric cables [7880] However due

to the limited availability of empirical studies it is difficult to theorize the extent of the impacts that

electro‐magnetic fields have on Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition of novel

vertical habitat to an area previously void of hard substratum Numerous studies have found greater

abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhua

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vesselmonitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing-related activities particularly artisanalfishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline ofMediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro-magnetic fieldsand novel habitat gain Recent studies have shown that the noise generated by pile driving during theconstruction phase of OWF farms can generate acute stress responses in juvenile fish species Althoughthe responses were recorded as acute it is possible that repeated and prolonged exposure in the wildmay lead to a decrease in fitness [72] During the operational stages of OWFs evidence indicates fishpermanently avoid wind turbines only at a range of up to 4 m under high wind speeds (13 msacute1) andthat their ability to communicate and utilize orientation signals is masked [67] Increased backgroundnoise and seabed vibration from operational OWFs and associated marine traffic will also influencefish detection distances [7374] (Figure 4) Greater numbers of experimental studies on individual fishspecies are needed before we can fully comprehend the impact of anthropogenic noise on fish [75]

Electromagnetic fields occur around intra-turbine array-to-transformer and transformer-to-shorecables The electro-sensitivity of many marine species is unknown and there is a dearth ofpeer-reviewed information regarding the effects of electro-magnetic fields Elasmobranchs are thoughtto be especially sensitive due to their electro-sensory organs [76] Several shark and ray species reactto wind farm cables [77] but whether this has any affect at the population level is unknown Magneticfields could influence geomagnetic patterns used by some migratory marine species for navigation [78]and reports also show that electro-magnetic fields from OWFs may affect fish migration Gill et al [79]identified eight migratory fish species sensitive to electromagnetic fields including the European eelAnguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus albacares Limitedin situ data are available about the actual effects on fish which rely on magnetic fields for migrationhowever several studies in the Baltic Sea have indicated that the swimming speed of European eels isreduced in the vicinity of underwater electric cables [7880] However due to the limited availabilityof empirical studies it is difficult to theorize the extent of the impacts that electro-magnetic fields haveon Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition ofnovel vertical habitat to an area previously void of hard substratum Numerous studies have foundgreater abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhuapouting Trisopterus luscus and several species of gobies [81ndash83] Currently most empirically measuredeffects due to operational wind turbines are temporally limited and not at the scale of OWFs [60]Several studies have implied that the new habitat provides increased foraging for both primaryand secondary food resources and protection grounds from currents [84] There is much discussion

J Mar Sci Eng 2016 4 18 9 of 17

between ecologists over whether changes in species biomass will be due to attraction or production [85]Stomach content analysis and energy profiling have shown that OWFs are suitable feeding groundsfor both Atlantic cod and pouting species [8687] indicating that there is extra biomass available at thesites Juvenile recruitment of Atlantic cod has also been observed at wind farms in the Belgium partof the North Sea [87] Changes in prey densities may also be masked by predation rates [6588] andwill potentially strengthen predator avoidance behaviors like diel migration further complicating therelationship between attraction-production dynamics [77] While the mechanics of fish abundanceat OWFs is not yet fully understood and requires additional analysis it is becoming increasinglyobvious that any ecological benefits will only be attained if fishing practices are banned within thewind farms [89]

For Mediterranean fish species it is difficult to state the effects based on the findings of NorthernEuropean studies as there is a limited availability of information and the majority of existingmonitoring programs focus on species that are not generally present in Mediterranean waters egAtlantic cod [828588] That being said there is evidence that suggests a yield increase of fishpopulations at wind farms as opposed to the simple attraction model previously hypothesized [8586]This is of particular importance for the Mediterranean as levels of fishing are unsustainable and mostfish stocks are in decline [71] The possibility for creating de facto marine protected areas (MPAs) due tofishing restrictions imposed within OWFs is an interesting aspect in the developments of OWFs in theMediterranean Sea It is clear that well protected MPAs in the Mediterranean result in significantlyhigher biomass than those with no or minimal protection [90] although many Mediterranean MPAslack adequate protection [91] Enforcement of fishing restrictions in Mediterranean MPAs is a difficultissue but the benefit associated with designating an area within a series of fixed structures is thatfishing regulations may be easier to enforce Benthic fishermen are less willing to drag their trawlinggear within turbines as they risk entanglement and there is a potential to monitor fishing activity ofstatic and recreational fishermen by using fixed cameras It is worth noting however that displacementof fishing effort is a serious concern for the management of reduced fishing effort regions [92]The production of sound by many fish species for communication during spawning periods means itis also essential for policy makers to identify fish spawning grounds during environmental impactassessments with the aim of restricting OWF construction in these noise-sensitive areas [93]

34 Potential Effects of Mediterranean Benthic Communities

The Mediterranean harbors many important benthic habitats including vermetid reefs coralligenicconcentrations shallow sublittoral rock seamounts deep-sea coral reefs and abyssal plains [9495]The shallow sub-littoral sediment is a particularly valuable habitat for the Mediterranean benthos as itis the preferred habitat of the endemic seagrass Posidonia oceanica listed as a priority natural habitatunder Annex 1 of the EC Habitats Directive (243EEC on the Conservation of Natural Habitatsand of Wild Fauna and Flora) due to its endemism high productivity and provision of ecosystemservices [9697] Favorable substrate conditions for OWF construction throughout Europe is typicallysoft sediment areas and the piling and drilling of foundations and monopile jackets constitutes the mostdirect impact to the marine environment As they favor similar habitats required for the constructionof OWFs Posidonia beds are at risk from direct physical destruction sedimentation and changes inhydrographic regimes Conversely construction may prevent local trawling and therefore decrease theamount of destructive fishing methods that typically reduces Posidonia coverage [98] Any plans forOWFs in the Mediterranean Sea will have to be carefully designed around the distribution of Posidoniato ensure the correct conservation practices for this endemic priority species

Other impacts to soft sediment communities from pre-construction states include changes inregional current regimes causing shifts in macro-benthic assemblages on a localized scale [99100]Studies have shown negative correlations between distance from turbines and grain sizes in the vicinityof turbines (measured from a distance from turbine of 15 m to 200 m) in the Belgian part of the NorthSea which were also positively correlated with increases in organic matter and a shift in species

J Mar Sci Eng 2016 4 18 10 of 17

assemblages The closer to the turbine the soft sediment community samples were taken the greaterthe increase in macrobenthic density and diversity [99]

Although changes in soft-sediment in-fauna are likely to be associated with wind farmconstruction the most direct affect is the addition of hard substratum to the environment Ecosystemshifts occur from changes in the existing soft sediment shifts and the addition of hard substratum ina habitat previously void of available settlement substratum Recruitment and colonization of novelartificial habitats provided by turbine foundations increases the structural complexity and productivityof an environment previously low in in-fauna diversity and density [101ndash110]

Research at an offshore research platform in the German Bight indicated that 35 times moremacro-zoobenthos biomass was associated with the additional hard substratum than the equivalentarea of soft benthic sediment [81] The increase in macro-zoobenthos biomass may appearbeneficial in regard to productivity yet in many cases species assemblages associated with artificialstructures differ from the environment replaced and show lower levels of diversity than natural rockequivalents [81110] Long-term effects of ecosystem shifts are unknown and species assemblagesare influenced by many parameters including material and texture of offshore structures larvalsupply oceanographic conditions temperature salinity and water depth [111] The number ofdefining parameters involved in influencing the spatial and temporal colonization of offshore artificialstructures highlights the need for extensive area-specific research and long-tem in situ experiments tofully understand regional implications of OWFs

With regard to the Mediterranean the limited investigative work into epibenthic colonization hasfocused on concrete artificial reefs [112ndash114] or rock anthropogenic structures [115116] Most studiesareas focus on the Northwestern region of the Mediterranean with the exception of two studies inTurkey and Israel [117118] Only two studies have investigated an offshore steel structure in theMediterranean [117118] Dominating species of epibenthic assemblages varied depending on thelocation and duration of monitoring program which ranged from 11 months to 20 years Most studiescited the initial establishment of Hydozoa Bryozoa and Serpulidae [112117ndash120] In several studiesinitial colonization was followed with the establishment and dominance of the commercially farmedMytilus galloprovincialis [112115119120] However the establishment of mussel beds on artificialstructures in the Mediterranean may be highly localized as several artificial structures showed no suchdominance [117121ndash123] or highly variable results [124] The only long-term data set on a concreteartificial reef (20 years) reported five distinct phases of species assemblage dominance of pioneerspecies mussel dominance mussel regression mussels absence and finally dominance of bryozoanbio-constructions [125] Differences in the material used for offshore structures may have a significanteffect on climax community composition the two offshore steel study sites in the Mediterraneanoffshore steel structures were both dominated by bivalves after 52 and 70 months [119121]

The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonizationof artificial substrata in the Mediterranean by alien species [122127] mean that wind farms may also actas benthic ldquostepping stonesrdquo that facilitate range extension of alien species within the Mediterraneanmarine environment which in turn may potentially reduce the biodiversity of the basin [111128]Due to the apparent locality factor of benthic colonization communites small-scale pilot studies areessential for understanding whether windfarms will proliferate alien species at potential wind farmlocations The use of before-after control-impact studies by policy makers is strongly recommended

35 Potential Effects of Mediterranean Planktonic Communities

The oxygen rich oligotrophic waters of the semi-enclosed Mediterranean produce a lownutrient availability that is however generally intensified along both a west-east and north-southdirection [129] There is nevertheless a high spatial heterogeneity in the distribution of planktonthroughout the Mediterranean Sea due to complex hydrodynamic circulation patterns formingmultiple gyres and upwelling systems [130] Most marine invertebrate and fish species havea planktonic larval stage therefore it is crucial to understand any effects OWFs may have on planktonic

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 4 of 17

a detectable change in seabird population trends Focus should preferably be given to understandingany direct effects OWFs will have on foraging success eg diving behavior and prey characteristicswhich in turn will impact reproductive success juvenile survival and population trends [20]

Table 1 Mediterranean seabird sensitivity assessments highlighting most and least vulnerable speciesaccording to index Y = Yes N = No Red = 10 most vulnerable Mediterranean species within indexBlue = 10 least vulnerable species within index ldquo-rdquo = Index not applied

Common Name Species EndemicListed under

BarcelonaConvention

Wind FarmSensitivityIndex [13]

VulnerabilityIndex forCollision

Impacts [30]

VulnerabilityIndex for

DisturbanceImpacts [30]

Coryrsquos Shearwater(Mediterranean)

Calonectris diomedeadiomedea Y Y - - -

YelkouanShearwater

(Mediterranean)Puffinus yelkouan Y N - - -

Balearic Shearwater Puffinusmauretanicus Y N - - -

European Shag(Mediterranean)

Phalacrocoraxaristotelis desmarestii Y Y - 150 14

Great Comorant Phalacrocorax carbo N N 233 - -

Pygmy Comorant Phalacrocoraxpygmeus N N - - -

Audouinrsquos gull Larus audouinii N Y - - -

Little Gull Hydrcoleus minutus N N 128 - -

Lesser black-backedgull Larus fuscus N N 138 960 3

Slender billed gull Larus genei N Y - - -

Mediterranean gull Larus melanocephalus N Y - - -

Black-headed gull Larus ridibundus N N 75 - -

Caspian gull Larus cachinnans N N - - -

Black leggedkittiwake Rissa tridactyla N N 75 -

Yellow legged gull Larus michahellis N N - - -

Great skua Catharacta skua N N - 320 3

Caspian tern Hydroprogne caspia N N - - -

Common tern Sterna hirundo N N 150 229 8

Little tern Sterna albifrons N N - 212 10

Sandwich tern Sterna sandvicensis N N 250 245 9

Lesser-crested tern Thalasseusbengalensis N N - -

Razorbill Alca torda N N 158 32 14

Atlantic puffin Fratercula arctica N N 150 27 10

European Stormpetrel

Hydrobates pelagicmelitensis Y Y - 91 2

Northern gannet Morus bassanus N N - - -

Osprey Pandion haliaetus N Y - - -

Eleanorersquos falcon Falco eleonorae N Y - - -

Red throated diver Gavia stellata N N 433 213 32

Black throated diver Gavia arctica N N 403 240 32

Great crested grebe Podicep scristatus N N 193 84 8

Red-necked grebe Podiceps grisegena N N 187 - -

Eared grebe Podiceps nigricollis N N - - -

J Mar Sci Eng 2016 4 18 5 of 17

Threats to Mediterranean bird populations are also directed towards migratory speciesWorldwide migratory species are declining in greater numbers than resident populations [34] and theMediterranean basin is a major transit route for Saharan-Eurasian migration as evidenced by both theMediterranean-Black Sea flyway and the Adriatic flyway [3536] Many long-distance bird migrantseg raptors and storks rely on land lift via thermal upwelling for long-distance flight [3738] andavoid broad fronts such as the Mediterranean Sea and the Saharan desert [37] creating bottlenecksat narrow passages of the Mediterranean Sea including Gibraltar the Straits of Sicily Messina (Italy)and the Belen pass (Turkey) [39] Wetlands around the Mediterranean provide suitable stopoversites for long-distance migrants to feed rest and molt [40] Some of the main wetlands around theMediterranean are located within close proximity of potential OWF hotspots particularly the Po Deltain the Northern Adriatic Sea the Nile Delta the Gabegraves Delta and the Camargue Delta in the Gulf ofLion (Figure 2) Due to the bathymetry of the Mediterranean and the steep continental slope of mostcoastlines deltas provide feasible sites for wind farm constructions High densities of avian habitatuse in these regions means that OWF resource overlap will be a key factor in Mediterranean marinespatial planning in regard to OWFs

J Mar Sci Eng 2016 4 18 5 of 17

Black throated

diver Gavia arctica N N 403 240 32

Great crested

grebe

Podicep

scristatus N N 193 84 8

Red‐necked grebe Podiceps

grisegena N N 187 ‐ ‐

Eared grebe Podiceps

nigricollis N N ‐ ‐ ‐

Threats to Mediterranean bird populations are also directed towards migratory species

Worldwide migratory species are declining in greater numbers than resident populations [34] and

the Mediterranean basin is a major transit route for Saharan‐Eurasian migration as evidenced by

both the Mediterranean‐Black Sea flyway and the Adriatic flyway [3536] Many long‐distance bird

migrants eg raptors and storks rely on land lift via thermal upwelling for long‐distance flight

[3738] and avoid broad fronts such as the Mediterranean Sea and the Saharan desert [37] creating

bottlenecks at narrow passages of the Mediterranean Sea including Gibraltar the Straits of Sicily

Messina (Italy) and the Belen pass (Turkey) [39] Wetlands around the Mediterranean provide

suitable stopover sites for long‐distance migrants to feed rest and molt [40] Some of the main

wetlands around the Mediterranean are located within close proximity of potential OWF hotspots

particularly the Po Delta in the Northern Adriatic Sea the Nile Delta the Gabegraves Delta and the

Camargue Delta in the Gulf of Lion (Figure 2) Due to the bathymetry of the Mediterranean and the

steep continental slope of most coastlines deltas provide feasible sites for wind farm constructions

High densities of avian habitat use in these regions means that OWF resource overlap will be a key

factor in Mediterranean marine spatial planning in regard to OWFs

Figure 2 Main Mediterranean wetlands and overlapping OWF potential hotspot areas (adapted from

[41] 1 Ebro Delta 2 Camargue Delta 3 Po Delta 4 Amvrakikos Gulf 5 Prespa Basin 6 Aliakmonas

Delta 7 Evros Delta 8 Gediz Delta 9 Gӧksu Delta 10 Seyhan Delta 11 Nile Delta 12 Gabegraves Delta

13 El Kala

High collision levels of migrating terrestrial birds at well‐lit observing platform during periods

of bad weather and poor visibility [42] indicate that wind farms located near the coast or prominent

migration bottlenecks may pose a significant risk to migrating birds More recent evidence also

shows alternative crossing options for some passerine species including non‐stop crossings over the

Mediterranean Sea [43] This indicates that species‐specific migrations are not fixed either temporally

or spatially and individual route decisions are due to risk analysis of many parameters including

energy reserves weather conditions and genetic disposition [4445] Until large‐scale migration

routes across the Mediterranean Sea are better understood developers face large difficulties in wind

farm spatial planning in the region Obtaining this information is an essential task for potential OWF

developers in the Mediterranean

Figure 2 Main Mediterranean wetlands and overlapping OWF potential hotspot areas (adaptedfrom [41] 1 Ebro Delta 2 Camargue Delta 3 Po Delta 4 Amvrakikos Gulf 5 Prespa Basin6 Aliakmonas Delta 7 Evros Delta 8 Gediz Delta 9 Goumlksu Delta 10 Seyhan Delta 11 Nile Delta12 Gabegraves Delta 13 El Kala

High collision levels of migrating terrestrial birds at well-lit observing platform during periodsof bad weather and poor visibility [42] indicate that wind farms located near the coast or prominentmigration bottlenecks may pose a significant risk to migrating birds More recent evidence alsoshows alternative crossing options for some passerine species including non-stop crossings over theMediterranean Sea [43] This indicates that species-specific migrations are not fixed either temporallyor spatially and individual route decisions are due to risk analysis of many parameters includingenergy reserves weather conditions and genetic disposition [4445] Until large-scale migration routesacross the Mediterranean Sea are better understood developers face large difficulties in wind farmspatial planning in the region Obtaining this information is an essential task for potential OWFdevelopers in the Mediterranean

Aside from identifying crucial regions for migrating birds one of the most poorly understoodaspects about OWF effects on birds is avoidance behavior Turbine avoidance tactics employed bya species may apply to both resident seabirds and long-distance migrants however any changesto migratory routes are extremely difficult to monitor and may have large indirect effects [42]Avoidance behavior is possible at several scales which are typically classified into micro mesoand macro strategies Micro-avoidance is the behavioral response to actively avoid rotating bladesMeso-avoidance is classified as behavior whereby species that fly at rotor height within the wind

J Mar Sci Eng 2016 4 18 6 of 17

farm and avoid the whole rotor swept zone and macro-avoidance being the behavioral alteration ofa flight path due to the presence of a wind farm [46] Macro-avoidance behavior strategies have beenshown in some migrating individuals The common eider Somateria mollissima for example exhibitedavoidance behaviors of a wind turbine at a range of up to 500 m during the day [47] The long-termconsequences of employing avoidance techniques remain unclear Among other parameters realimpacts to population trends of migrating birds will be highly dependent on the specific life historiesof a species expenditure of avoidance strategies energy reserves and weather conditions duringmigratory periods

There are several possible measures to reduce the effects wind farms will have on Mediterraneanavian populations eg shutdown orders and changes to the phototaxis level of structures [4849]However preventative initiatives are much more effective ie ensuring planning and placementof OWFs are not in the vicinity of large population of species that have been identified as high riskwithin the Mediterranean The sensitive species suggested here due to collision or habitat vulnerabilityinclude the lesser black-backed gull the Northern gannet and the red- and black-throated divers whilethe endemic bird species and species whose populations are declining in recent decades (Shearwaters)are identified due to their conservation importance (Table 1) More understanding of the cumulativeeffects of all impacts at all potential development sites is needed Until then all future approaches inregard to OWF spatial planning in the Mediterranean should be of a cautionary nature

32 Potential Effects of Mediterranean Marine Mammals

Marine mammals are often high profile charismatic species and have the potential for highsocio-economic value in their natural habitats [50] It is therefore essential to understand the effectsOWFs will have on Mediterranean populations The Mediterranean Sea is home to both resident andvisiting marine mammals of which most are experiencing a decline in population trends with theexception of visiting humpback whales whose numbers have appeared to increase [1151] At a basinlevel total population numbers are difficult to assess with several species being classified as ldquodatadeficientrdquo by the IUCN red list [20] Nonetheless certain regions have been identified as importanthabitats for marine mammals Monitoring programs show a high percentage of fin whale sightingswithin the Ligurian Sea in comparison with other regions of the Mediterranean Sea [52] The AlboreanSea has been shown to be an important for long-finned pilot whale populations [53] and there is alsoevidence that due to the East-West basin migration of Sperm whales either the Strait of Sicily or theStrait of Messina are critical areas which enable migration [54]

In regard to OWF development several resident marine mammals frequently use the coastalmarine environment earmarked for potential developments including the critically endangeredMediterranean monk seal the common Bottlenose dolphin and visiting Humpback whales [515556]When assessing the combined species density of the resident marine mammals the Gulf of Lion OWFhotspot displays the highest densities of resident marine mammals and as such can be considered asthe most sensitive in regard to OWF development The Gulfs of Hammamet and Gabegraves the Gulf ofSidra and the Nile Delta hotspots appear to support low populations of resident marine mammals(Figure 3)

The distribution of specific species of marine mammals is also of interest to developers This isparticularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently usesthe coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the coast ofTrieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include the thecoast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These regionswill require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise andin particular pile driving during construction has been identified as the biggest impact to marinemammals [58] Increased motorized vessel shipping during the operational phase of wind farms alsoincreases noise levels to the area and so is also identified as an impact however this is not at a level

J Mar Sci Eng 2016 4 18 7 of 17

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the speciespile driven construction has the ability to produce hearing impairment although for most specieshearing reactions are as yet undetermined [60]J Mar Sci Eng 2016 4 18 7 of 17

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Image

adapted from Coll et al [11])

The distribution of specific species of marine mammals is also of interest to developers This is

particularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently

uses the coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the

coast of Trieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include

the the coast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These

regions will require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise and in

particular pile driving during construction has been identified as the biggest impact to marine

mammals [58] Increased motorized vessel shipping during the operational phase of wind farms also

increases noise levels to the area and so is also identified as an impact however this is not at a level

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the species

pile driven construction has the ability to produce hearing impairment although for most species

hearing reactions are as yet undetermined [60]

A study measuring the propagation of sound during the construction phase of an offshore site

in the NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range

of the site and behavior disturbances up to 50 km away [61] With the use of T‐POD porpoise

detectors acoustic monitoring during the construction and into the operational phase of the Nysted

OWF indicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a

reduction in the level of echolocation signals produced by the porpoises [62] A long‐term study (10

years) at the same wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measured

significantly higher acoustic activity inside the farm in comparison with a control site [64] and this

trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggested an

increase in habitat utilization at two operational wind farms (Alpha Ventus and Sheringham Shoal)

[65] The repeated grid‐like movements indicated for the first time successful foraging behavior by

an apex predator within an OWF The apparent differences between probable habitat uses may be

due to local‐scale ecological differences local population habituation of wind farms or differences in

construction type of wind farms [64] Due to critical population levels in the Mediterranean the

observed increases in seal foraging behavior around wind farms may not be relevant to the

Mediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi‐enclosed Mediterranean

also suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In

general noise from wind farms is influenced by water depth wind speed turbine type wind farm

size and substratum type [67] due to the high levels of existing background noise from maritime

traffic in the Mediterranean risks having a cumulative effect in masking communicative abilities of

marine species [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots

of the Gulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels

within the area (up to 140 m vessels∙kmminus2∙dayminus1) thus high levels of background noise can be expected

in these regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levels

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Imageadapted from Coll et al [11])

A study measuring the propagation of sound during the construction phase of an offshore site inthe NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range ofthe site and behavior disturbances up to 50 km away [61] With the use of T-POD porpoise detectorsacoustic monitoring during the construction and into the operational phase of the Nysted OWFindicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a reductionin the level of echolocation signals produced by the porpoises [62] A long-term study (10 years) at thesame wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measuredsignificantly higher acoustic activity inside the farm in comparison with a control site [64] andthis trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggestedan increase in habitat utilization at two operational wind farms (Alpha Ventus and SheringhamShoal) [65] The repeated grid-like movements indicated for the first time successful foraging behaviorby an apex predator within an OWF The apparent differences between probable habitat uses may bedue to local-scale ecological differences local population habituation of wind farms or differencesin construction type of wind farms [64] Due to critical population levels in the Mediterraneanthe observed increases in seal foraging behavior around wind farms may not be relevant to theMediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi-enclosed Mediterraneanalso suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In generalnoise from wind farms is influenced by water depth wind speed turbine type wind farm size andsubstratum type [67] due to the high levels of existing background noise from maritime traffic inthe Mediterranean risks having a cumulative effect in masking communicative abilities of marinespecies [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots of theGulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels withinthe area (up to 140 m vesselsuml kmacute2uml dayacute1) thus high levels of background noise can be expected inthese regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levelsof background noise stress The use of underwater noise propagation models by policy makers willbe required to understand the combined influence of OWF construction operation and maintenanceshipping with current levels of background noise at site-specific locations

J Mar Sci Eng 2016 4 18 8 of 17

J Mar Sci Eng 2016 4 18 8 of 17

of background noise stress The use of underwater noise propagation models by policy makers will

be required to understand the combined influence of OWF construction operation and maintenance

shipping with current levels of background noise at site‐specific locations

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vessel

monitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing‐related activities particularly artisanal

fishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean

8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline of

Mediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro‐magnetic

fields and novel habitat gain Recent studies have shown that the noise generated by pile driving

during the construction phase of OWF farms can generate acute stress responses in juvenile fish

species Although the responses were recorded as acute it is possible that repeated and prolonged

exposure in the wild may lead to a decrease in fitness [72] During the operational stages of OWFs

evidence indicates fish permanently avoid wind turbines only at a range of up to 4 m under high

wind speeds (13 msminus1) and that their ability to communicate and utilize orientation signals is masked

[67] Increased background noise and seabed vibration from operational OWFs and associated marine

traffic will also influence fish detection distances [7374] (Figure 4) Greater numbers of experimental

studies on individual fish species are needed before we can fully comprehend the impact of

anthropogenic noise on fish [75]

Electromagnetic fields occur around intra‐turbine array‐to‐transformer and transformer‐to‐

shore cables The electro‐sensitivity of many marine species is unknown and there is a dearth of peer‐

reviewed information regarding the effects of electro‐magnetic fields Elasmobranchs are thought to

be especially sensitive due to their electro‐sensory organs [76] Several shark and ray species react to

wind farm cables [77] but whether this has any affect at the population level is unknown Magnetic

fields could influence geomagnetic patterns used by some migratory marine species for navigation

[78] and reports also show that electro‐magnetic fields from OWFs may affect fish migration Gill et

al [79] identified eight migratory fish species sensitive to electromagnetic fields including the

European eel Anguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus

albacares Limited in situ data are available about the actual effects on fish which rely on magnetic

fields for migration however several studies in the Baltic Sea have indicated that the swimming

speed of European eels is reduced in the vicinity of underwater electric cables [7880] However due

to the limited availability of empirical studies it is difficult to theorize the extent of the impacts that

electro‐magnetic fields have on Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition of novel

vertical habitat to an area previously void of hard substratum Numerous studies have found greater

abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhua

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vesselmonitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing-related activities particularly artisanalfishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline ofMediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro-magnetic fieldsand novel habitat gain Recent studies have shown that the noise generated by pile driving during theconstruction phase of OWF farms can generate acute stress responses in juvenile fish species Althoughthe responses were recorded as acute it is possible that repeated and prolonged exposure in the wildmay lead to a decrease in fitness [72] During the operational stages of OWFs evidence indicates fishpermanently avoid wind turbines only at a range of up to 4 m under high wind speeds (13 msacute1) andthat their ability to communicate and utilize orientation signals is masked [67] Increased backgroundnoise and seabed vibration from operational OWFs and associated marine traffic will also influencefish detection distances [7374] (Figure 4) Greater numbers of experimental studies on individual fishspecies are needed before we can fully comprehend the impact of anthropogenic noise on fish [75]

Electromagnetic fields occur around intra-turbine array-to-transformer and transformer-to-shorecables The electro-sensitivity of many marine species is unknown and there is a dearth ofpeer-reviewed information regarding the effects of electro-magnetic fields Elasmobranchs are thoughtto be especially sensitive due to their electro-sensory organs [76] Several shark and ray species reactto wind farm cables [77] but whether this has any affect at the population level is unknown Magneticfields could influence geomagnetic patterns used by some migratory marine species for navigation [78]and reports also show that electro-magnetic fields from OWFs may affect fish migration Gill et al [79]identified eight migratory fish species sensitive to electromagnetic fields including the European eelAnguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus albacares Limitedin situ data are available about the actual effects on fish which rely on magnetic fields for migrationhowever several studies in the Baltic Sea have indicated that the swimming speed of European eels isreduced in the vicinity of underwater electric cables [7880] However due to the limited availabilityof empirical studies it is difficult to theorize the extent of the impacts that electro-magnetic fields haveon Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition ofnovel vertical habitat to an area previously void of hard substratum Numerous studies have foundgreater abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhuapouting Trisopterus luscus and several species of gobies [81ndash83] Currently most empirically measuredeffects due to operational wind turbines are temporally limited and not at the scale of OWFs [60]Several studies have implied that the new habitat provides increased foraging for both primaryand secondary food resources and protection grounds from currents [84] There is much discussion

J Mar Sci Eng 2016 4 18 9 of 17

between ecologists over whether changes in species biomass will be due to attraction or production [85]Stomach content analysis and energy profiling have shown that OWFs are suitable feeding groundsfor both Atlantic cod and pouting species [8687] indicating that there is extra biomass available at thesites Juvenile recruitment of Atlantic cod has also been observed at wind farms in the Belgium partof the North Sea [87] Changes in prey densities may also be masked by predation rates [6588] andwill potentially strengthen predator avoidance behaviors like diel migration further complicating therelationship between attraction-production dynamics [77] While the mechanics of fish abundanceat OWFs is not yet fully understood and requires additional analysis it is becoming increasinglyobvious that any ecological benefits will only be attained if fishing practices are banned within thewind farms [89]

For Mediterranean fish species it is difficult to state the effects based on the findings of NorthernEuropean studies as there is a limited availability of information and the majority of existingmonitoring programs focus on species that are not generally present in Mediterranean waters egAtlantic cod [828588] That being said there is evidence that suggests a yield increase of fishpopulations at wind farms as opposed to the simple attraction model previously hypothesized [8586]This is of particular importance for the Mediterranean as levels of fishing are unsustainable and mostfish stocks are in decline [71] The possibility for creating de facto marine protected areas (MPAs) due tofishing restrictions imposed within OWFs is an interesting aspect in the developments of OWFs in theMediterranean Sea It is clear that well protected MPAs in the Mediterranean result in significantlyhigher biomass than those with no or minimal protection [90] although many Mediterranean MPAslack adequate protection [91] Enforcement of fishing restrictions in Mediterranean MPAs is a difficultissue but the benefit associated with designating an area within a series of fixed structures is thatfishing regulations may be easier to enforce Benthic fishermen are less willing to drag their trawlinggear within turbines as they risk entanglement and there is a potential to monitor fishing activity ofstatic and recreational fishermen by using fixed cameras It is worth noting however that displacementof fishing effort is a serious concern for the management of reduced fishing effort regions [92]The production of sound by many fish species for communication during spawning periods means itis also essential for policy makers to identify fish spawning grounds during environmental impactassessments with the aim of restricting OWF construction in these noise-sensitive areas [93]

34 Potential Effects of Mediterranean Benthic Communities

The Mediterranean harbors many important benthic habitats including vermetid reefs coralligenicconcentrations shallow sublittoral rock seamounts deep-sea coral reefs and abyssal plains [9495]The shallow sub-littoral sediment is a particularly valuable habitat for the Mediterranean benthos as itis the preferred habitat of the endemic seagrass Posidonia oceanica listed as a priority natural habitatunder Annex 1 of the EC Habitats Directive (243EEC on the Conservation of Natural Habitatsand of Wild Fauna and Flora) due to its endemism high productivity and provision of ecosystemservices [9697] Favorable substrate conditions for OWF construction throughout Europe is typicallysoft sediment areas and the piling and drilling of foundations and monopile jackets constitutes the mostdirect impact to the marine environment As they favor similar habitats required for the constructionof OWFs Posidonia beds are at risk from direct physical destruction sedimentation and changes inhydrographic regimes Conversely construction may prevent local trawling and therefore decrease theamount of destructive fishing methods that typically reduces Posidonia coverage [98] Any plans forOWFs in the Mediterranean Sea will have to be carefully designed around the distribution of Posidoniato ensure the correct conservation practices for this endemic priority species

Other impacts to soft sediment communities from pre-construction states include changes inregional current regimes causing shifts in macro-benthic assemblages on a localized scale [99100]Studies have shown negative correlations between distance from turbines and grain sizes in the vicinityof turbines (measured from a distance from turbine of 15 m to 200 m) in the Belgian part of the NorthSea which were also positively correlated with increases in organic matter and a shift in species

J Mar Sci Eng 2016 4 18 10 of 17

assemblages The closer to the turbine the soft sediment community samples were taken the greaterthe increase in macrobenthic density and diversity [99]

Although changes in soft-sediment in-fauna are likely to be associated with wind farmconstruction the most direct affect is the addition of hard substratum to the environment Ecosystemshifts occur from changes in the existing soft sediment shifts and the addition of hard substratum ina habitat previously void of available settlement substratum Recruitment and colonization of novelartificial habitats provided by turbine foundations increases the structural complexity and productivityof an environment previously low in in-fauna diversity and density [101ndash110]

Research at an offshore research platform in the German Bight indicated that 35 times moremacro-zoobenthos biomass was associated with the additional hard substratum than the equivalentarea of soft benthic sediment [81] The increase in macro-zoobenthos biomass may appearbeneficial in regard to productivity yet in many cases species assemblages associated with artificialstructures differ from the environment replaced and show lower levels of diversity than natural rockequivalents [81110] Long-term effects of ecosystem shifts are unknown and species assemblagesare influenced by many parameters including material and texture of offshore structures larvalsupply oceanographic conditions temperature salinity and water depth [111] The number ofdefining parameters involved in influencing the spatial and temporal colonization of offshore artificialstructures highlights the need for extensive area-specific research and long-tem in situ experiments tofully understand regional implications of OWFs

With regard to the Mediterranean the limited investigative work into epibenthic colonization hasfocused on concrete artificial reefs [112ndash114] or rock anthropogenic structures [115116] Most studiesareas focus on the Northwestern region of the Mediterranean with the exception of two studies inTurkey and Israel [117118] Only two studies have investigated an offshore steel structure in theMediterranean [117118] Dominating species of epibenthic assemblages varied depending on thelocation and duration of monitoring program which ranged from 11 months to 20 years Most studiescited the initial establishment of Hydozoa Bryozoa and Serpulidae [112117ndash120] In several studiesinitial colonization was followed with the establishment and dominance of the commercially farmedMytilus galloprovincialis [112115119120] However the establishment of mussel beds on artificialstructures in the Mediterranean may be highly localized as several artificial structures showed no suchdominance [117121ndash123] or highly variable results [124] The only long-term data set on a concreteartificial reef (20 years) reported five distinct phases of species assemblage dominance of pioneerspecies mussel dominance mussel regression mussels absence and finally dominance of bryozoanbio-constructions [125] Differences in the material used for offshore structures may have a significanteffect on climax community composition the two offshore steel study sites in the Mediterraneanoffshore steel structures were both dominated by bivalves after 52 and 70 months [119121]

The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonizationof artificial substrata in the Mediterranean by alien species [122127] mean that wind farms may also actas benthic ldquostepping stonesrdquo that facilitate range extension of alien species within the Mediterraneanmarine environment which in turn may potentially reduce the biodiversity of the basin [111128]Due to the apparent locality factor of benthic colonization communites small-scale pilot studies areessential for understanding whether windfarms will proliferate alien species at potential wind farmlocations The use of before-after control-impact studies by policy makers is strongly recommended

35 Potential Effects of Mediterranean Planktonic Communities

The oxygen rich oligotrophic waters of the semi-enclosed Mediterranean produce a lownutrient availability that is however generally intensified along both a west-east and north-southdirection [129] There is nevertheless a high spatial heterogeneity in the distribution of planktonthroughout the Mediterranean Sea due to complex hydrodynamic circulation patterns formingmultiple gyres and upwelling systems [130] Most marine invertebrate and fish species havea planktonic larval stage therefore it is crucial to understand any effects OWFs may have on planktonic

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 5 of 17

Threats to Mediterranean bird populations are also directed towards migratory speciesWorldwide migratory species are declining in greater numbers than resident populations [34] and theMediterranean basin is a major transit route for Saharan-Eurasian migration as evidenced by both theMediterranean-Black Sea flyway and the Adriatic flyway [3536] Many long-distance bird migrantseg raptors and storks rely on land lift via thermal upwelling for long-distance flight [3738] andavoid broad fronts such as the Mediterranean Sea and the Saharan desert [37] creating bottlenecksat narrow passages of the Mediterranean Sea including Gibraltar the Straits of Sicily Messina (Italy)and the Belen pass (Turkey) [39] Wetlands around the Mediterranean provide suitable stopoversites for long-distance migrants to feed rest and molt [40] Some of the main wetlands around theMediterranean are located within close proximity of potential OWF hotspots particularly the Po Deltain the Northern Adriatic Sea the Nile Delta the Gabegraves Delta and the Camargue Delta in the Gulf ofLion (Figure 2) Due to the bathymetry of the Mediterranean and the steep continental slope of mostcoastlines deltas provide feasible sites for wind farm constructions High densities of avian habitatuse in these regions means that OWF resource overlap will be a key factor in Mediterranean marinespatial planning in regard to OWFs

J Mar Sci Eng 2016 4 18 5 of 17

Black throated

diver Gavia arctica N N 403 240 32

Great crested

grebe

Podicep

scristatus N N 193 84 8

Red‐necked grebe Podiceps

grisegena N N 187 ‐ ‐

Eared grebe Podiceps

nigricollis N N ‐ ‐ ‐

Threats to Mediterranean bird populations are also directed towards migratory species

Worldwide migratory species are declining in greater numbers than resident populations [34] and

the Mediterranean basin is a major transit route for Saharan‐Eurasian migration as evidenced by

both the Mediterranean‐Black Sea flyway and the Adriatic flyway [3536] Many long‐distance bird

migrants eg raptors and storks rely on land lift via thermal upwelling for long‐distance flight

[3738] and avoid broad fronts such as the Mediterranean Sea and the Saharan desert [37] creating

bottlenecks at narrow passages of the Mediterranean Sea including Gibraltar the Straits of Sicily

Messina (Italy) and the Belen pass (Turkey) [39] Wetlands around the Mediterranean provide

suitable stopover sites for long‐distance migrants to feed rest and molt [40] Some of the main

wetlands around the Mediterranean are located within close proximity of potential OWF hotspots

particularly the Po Delta in the Northern Adriatic Sea the Nile Delta the Gabegraves Delta and the

Camargue Delta in the Gulf of Lion (Figure 2) Due to the bathymetry of the Mediterranean and the

steep continental slope of most coastlines deltas provide feasible sites for wind farm constructions

High densities of avian habitat use in these regions means that OWF resource overlap will be a key

factor in Mediterranean marine spatial planning in regard to OWFs

Figure 2 Main Mediterranean wetlands and overlapping OWF potential hotspot areas (adapted from

[41] 1 Ebro Delta 2 Camargue Delta 3 Po Delta 4 Amvrakikos Gulf 5 Prespa Basin 6 Aliakmonas

Delta 7 Evros Delta 8 Gediz Delta 9 Gӧksu Delta 10 Seyhan Delta 11 Nile Delta 12 Gabegraves Delta

13 El Kala

High collision levels of migrating terrestrial birds at well‐lit observing platform during periods

of bad weather and poor visibility [42] indicate that wind farms located near the coast or prominent

migration bottlenecks may pose a significant risk to migrating birds More recent evidence also

shows alternative crossing options for some passerine species including non‐stop crossings over the

Mediterranean Sea [43] This indicates that species‐specific migrations are not fixed either temporally

or spatially and individual route decisions are due to risk analysis of many parameters including

energy reserves weather conditions and genetic disposition [4445] Until large‐scale migration

routes across the Mediterranean Sea are better understood developers face large difficulties in wind

farm spatial planning in the region Obtaining this information is an essential task for potential OWF

developers in the Mediterranean

Figure 2 Main Mediterranean wetlands and overlapping OWF potential hotspot areas (adaptedfrom [41] 1 Ebro Delta 2 Camargue Delta 3 Po Delta 4 Amvrakikos Gulf 5 Prespa Basin6 Aliakmonas Delta 7 Evros Delta 8 Gediz Delta 9 Goumlksu Delta 10 Seyhan Delta 11 Nile Delta12 Gabegraves Delta 13 El Kala

High collision levels of migrating terrestrial birds at well-lit observing platform during periodsof bad weather and poor visibility [42] indicate that wind farms located near the coast or prominentmigration bottlenecks may pose a significant risk to migrating birds More recent evidence alsoshows alternative crossing options for some passerine species including non-stop crossings over theMediterranean Sea [43] This indicates that species-specific migrations are not fixed either temporallyor spatially and individual route decisions are due to risk analysis of many parameters includingenergy reserves weather conditions and genetic disposition [4445] Until large-scale migration routesacross the Mediterranean Sea are better understood developers face large difficulties in wind farmspatial planning in the region Obtaining this information is an essential task for potential OWFdevelopers in the Mediterranean

Aside from identifying crucial regions for migrating birds one of the most poorly understoodaspects about OWF effects on birds is avoidance behavior Turbine avoidance tactics employed bya species may apply to both resident seabirds and long-distance migrants however any changesto migratory routes are extremely difficult to monitor and may have large indirect effects [42]Avoidance behavior is possible at several scales which are typically classified into micro mesoand macro strategies Micro-avoidance is the behavioral response to actively avoid rotating bladesMeso-avoidance is classified as behavior whereby species that fly at rotor height within the wind

J Mar Sci Eng 2016 4 18 6 of 17

farm and avoid the whole rotor swept zone and macro-avoidance being the behavioral alteration ofa flight path due to the presence of a wind farm [46] Macro-avoidance behavior strategies have beenshown in some migrating individuals The common eider Somateria mollissima for example exhibitedavoidance behaviors of a wind turbine at a range of up to 500 m during the day [47] The long-termconsequences of employing avoidance techniques remain unclear Among other parameters realimpacts to population trends of migrating birds will be highly dependent on the specific life historiesof a species expenditure of avoidance strategies energy reserves and weather conditions duringmigratory periods

There are several possible measures to reduce the effects wind farms will have on Mediterraneanavian populations eg shutdown orders and changes to the phototaxis level of structures [4849]However preventative initiatives are much more effective ie ensuring planning and placementof OWFs are not in the vicinity of large population of species that have been identified as high riskwithin the Mediterranean The sensitive species suggested here due to collision or habitat vulnerabilityinclude the lesser black-backed gull the Northern gannet and the red- and black-throated divers whilethe endemic bird species and species whose populations are declining in recent decades (Shearwaters)are identified due to their conservation importance (Table 1) More understanding of the cumulativeeffects of all impacts at all potential development sites is needed Until then all future approaches inregard to OWF spatial planning in the Mediterranean should be of a cautionary nature

32 Potential Effects of Mediterranean Marine Mammals

Marine mammals are often high profile charismatic species and have the potential for highsocio-economic value in their natural habitats [50] It is therefore essential to understand the effectsOWFs will have on Mediterranean populations The Mediterranean Sea is home to both resident andvisiting marine mammals of which most are experiencing a decline in population trends with theexception of visiting humpback whales whose numbers have appeared to increase [1151] At a basinlevel total population numbers are difficult to assess with several species being classified as ldquodatadeficientrdquo by the IUCN red list [20] Nonetheless certain regions have been identified as importanthabitats for marine mammals Monitoring programs show a high percentage of fin whale sightingswithin the Ligurian Sea in comparison with other regions of the Mediterranean Sea [52] The AlboreanSea has been shown to be an important for long-finned pilot whale populations [53] and there is alsoevidence that due to the East-West basin migration of Sperm whales either the Strait of Sicily or theStrait of Messina are critical areas which enable migration [54]

In regard to OWF development several resident marine mammals frequently use the coastalmarine environment earmarked for potential developments including the critically endangeredMediterranean monk seal the common Bottlenose dolphin and visiting Humpback whales [515556]When assessing the combined species density of the resident marine mammals the Gulf of Lion OWFhotspot displays the highest densities of resident marine mammals and as such can be considered asthe most sensitive in regard to OWF development The Gulfs of Hammamet and Gabegraves the Gulf ofSidra and the Nile Delta hotspots appear to support low populations of resident marine mammals(Figure 3)

The distribution of specific species of marine mammals is also of interest to developers This isparticularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently usesthe coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the coast ofTrieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include the thecoast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These regionswill require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise andin particular pile driving during construction has been identified as the biggest impact to marinemammals [58] Increased motorized vessel shipping during the operational phase of wind farms alsoincreases noise levels to the area and so is also identified as an impact however this is not at a level

J Mar Sci Eng 2016 4 18 7 of 17

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the speciespile driven construction has the ability to produce hearing impairment although for most specieshearing reactions are as yet undetermined [60]J Mar Sci Eng 2016 4 18 7 of 17

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Image

adapted from Coll et al [11])

The distribution of specific species of marine mammals is also of interest to developers This is

particularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently

uses the coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the

coast of Trieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include

the the coast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These

regions will require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise and in

particular pile driving during construction has been identified as the biggest impact to marine

mammals [58] Increased motorized vessel shipping during the operational phase of wind farms also

increases noise levels to the area and so is also identified as an impact however this is not at a level

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the species

pile driven construction has the ability to produce hearing impairment although for most species

hearing reactions are as yet undetermined [60]

A study measuring the propagation of sound during the construction phase of an offshore site

in the NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range

of the site and behavior disturbances up to 50 km away [61] With the use of T‐POD porpoise

detectors acoustic monitoring during the construction and into the operational phase of the Nysted

OWF indicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a

reduction in the level of echolocation signals produced by the porpoises [62] A long‐term study (10

years) at the same wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measured

significantly higher acoustic activity inside the farm in comparison with a control site [64] and this

trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggested an

increase in habitat utilization at two operational wind farms (Alpha Ventus and Sheringham Shoal)

[65] The repeated grid‐like movements indicated for the first time successful foraging behavior by

an apex predator within an OWF The apparent differences between probable habitat uses may be

due to local‐scale ecological differences local population habituation of wind farms or differences in

construction type of wind farms [64] Due to critical population levels in the Mediterranean the

observed increases in seal foraging behavior around wind farms may not be relevant to the

Mediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi‐enclosed Mediterranean

also suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In

general noise from wind farms is influenced by water depth wind speed turbine type wind farm

size and substratum type [67] due to the high levels of existing background noise from maritime

traffic in the Mediterranean risks having a cumulative effect in masking communicative abilities of

marine species [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots

of the Gulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels

within the area (up to 140 m vessels∙kmminus2∙dayminus1) thus high levels of background noise can be expected

in these regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levels

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Imageadapted from Coll et al [11])

A study measuring the propagation of sound during the construction phase of an offshore site inthe NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range ofthe site and behavior disturbances up to 50 km away [61] With the use of T-POD porpoise detectorsacoustic monitoring during the construction and into the operational phase of the Nysted OWFindicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a reductionin the level of echolocation signals produced by the porpoises [62] A long-term study (10 years) at thesame wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measuredsignificantly higher acoustic activity inside the farm in comparison with a control site [64] andthis trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggestedan increase in habitat utilization at two operational wind farms (Alpha Ventus and SheringhamShoal) [65] The repeated grid-like movements indicated for the first time successful foraging behaviorby an apex predator within an OWF The apparent differences between probable habitat uses may bedue to local-scale ecological differences local population habituation of wind farms or differencesin construction type of wind farms [64] Due to critical population levels in the Mediterraneanthe observed increases in seal foraging behavior around wind farms may not be relevant to theMediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi-enclosed Mediterraneanalso suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In generalnoise from wind farms is influenced by water depth wind speed turbine type wind farm size andsubstratum type [67] due to the high levels of existing background noise from maritime traffic inthe Mediterranean risks having a cumulative effect in masking communicative abilities of marinespecies [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots of theGulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels withinthe area (up to 140 m vesselsuml kmacute2uml dayacute1) thus high levels of background noise can be expected inthese regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levelsof background noise stress The use of underwater noise propagation models by policy makers willbe required to understand the combined influence of OWF construction operation and maintenanceshipping with current levels of background noise at site-specific locations

J Mar Sci Eng 2016 4 18 8 of 17

J Mar Sci Eng 2016 4 18 8 of 17

of background noise stress The use of underwater noise propagation models by policy makers will

be required to understand the combined influence of OWF construction operation and maintenance

shipping with current levels of background noise at site‐specific locations

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vessel

monitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing‐related activities particularly artisanal

fishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean

8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline of

Mediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro‐magnetic

fields and novel habitat gain Recent studies have shown that the noise generated by pile driving

during the construction phase of OWF farms can generate acute stress responses in juvenile fish

species Although the responses were recorded as acute it is possible that repeated and prolonged

exposure in the wild may lead to a decrease in fitness [72] During the operational stages of OWFs

evidence indicates fish permanently avoid wind turbines only at a range of up to 4 m under high

wind speeds (13 msminus1) and that their ability to communicate and utilize orientation signals is masked

[67] Increased background noise and seabed vibration from operational OWFs and associated marine

traffic will also influence fish detection distances [7374] (Figure 4) Greater numbers of experimental

studies on individual fish species are needed before we can fully comprehend the impact of

anthropogenic noise on fish [75]

Electromagnetic fields occur around intra‐turbine array‐to‐transformer and transformer‐to‐

shore cables The electro‐sensitivity of many marine species is unknown and there is a dearth of peer‐

reviewed information regarding the effects of electro‐magnetic fields Elasmobranchs are thought to

be especially sensitive due to their electro‐sensory organs [76] Several shark and ray species react to

wind farm cables [77] but whether this has any affect at the population level is unknown Magnetic

fields could influence geomagnetic patterns used by some migratory marine species for navigation

[78] and reports also show that electro‐magnetic fields from OWFs may affect fish migration Gill et

al [79] identified eight migratory fish species sensitive to electromagnetic fields including the

European eel Anguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus

albacares Limited in situ data are available about the actual effects on fish which rely on magnetic

fields for migration however several studies in the Baltic Sea have indicated that the swimming

speed of European eels is reduced in the vicinity of underwater electric cables [7880] However due

to the limited availability of empirical studies it is difficult to theorize the extent of the impacts that

electro‐magnetic fields have on Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition of novel

vertical habitat to an area previously void of hard substratum Numerous studies have found greater

abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhua

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vesselmonitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing-related activities particularly artisanalfishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline ofMediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro-magnetic fieldsand novel habitat gain Recent studies have shown that the noise generated by pile driving during theconstruction phase of OWF farms can generate acute stress responses in juvenile fish species Althoughthe responses were recorded as acute it is possible that repeated and prolonged exposure in the wildmay lead to a decrease in fitness [72] During the operational stages of OWFs evidence indicates fishpermanently avoid wind turbines only at a range of up to 4 m under high wind speeds (13 msacute1) andthat their ability to communicate and utilize orientation signals is masked [67] Increased backgroundnoise and seabed vibration from operational OWFs and associated marine traffic will also influencefish detection distances [7374] (Figure 4) Greater numbers of experimental studies on individual fishspecies are needed before we can fully comprehend the impact of anthropogenic noise on fish [75]

Electromagnetic fields occur around intra-turbine array-to-transformer and transformer-to-shorecables The electro-sensitivity of many marine species is unknown and there is a dearth ofpeer-reviewed information regarding the effects of electro-magnetic fields Elasmobranchs are thoughtto be especially sensitive due to their electro-sensory organs [76] Several shark and ray species reactto wind farm cables [77] but whether this has any affect at the population level is unknown Magneticfields could influence geomagnetic patterns used by some migratory marine species for navigation [78]and reports also show that electro-magnetic fields from OWFs may affect fish migration Gill et al [79]identified eight migratory fish species sensitive to electromagnetic fields including the European eelAnguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus albacares Limitedin situ data are available about the actual effects on fish which rely on magnetic fields for migrationhowever several studies in the Baltic Sea have indicated that the swimming speed of European eels isreduced in the vicinity of underwater electric cables [7880] However due to the limited availabilityof empirical studies it is difficult to theorize the extent of the impacts that electro-magnetic fields haveon Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition ofnovel vertical habitat to an area previously void of hard substratum Numerous studies have foundgreater abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhuapouting Trisopterus luscus and several species of gobies [81ndash83] Currently most empirically measuredeffects due to operational wind turbines are temporally limited and not at the scale of OWFs [60]Several studies have implied that the new habitat provides increased foraging for both primaryand secondary food resources and protection grounds from currents [84] There is much discussion

J Mar Sci Eng 2016 4 18 9 of 17

between ecologists over whether changes in species biomass will be due to attraction or production [85]Stomach content analysis and energy profiling have shown that OWFs are suitable feeding groundsfor both Atlantic cod and pouting species [8687] indicating that there is extra biomass available at thesites Juvenile recruitment of Atlantic cod has also been observed at wind farms in the Belgium partof the North Sea [87] Changes in prey densities may also be masked by predation rates [6588] andwill potentially strengthen predator avoidance behaviors like diel migration further complicating therelationship between attraction-production dynamics [77] While the mechanics of fish abundanceat OWFs is not yet fully understood and requires additional analysis it is becoming increasinglyobvious that any ecological benefits will only be attained if fishing practices are banned within thewind farms [89]

For Mediterranean fish species it is difficult to state the effects based on the findings of NorthernEuropean studies as there is a limited availability of information and the majority of existingmonitoring programs focus on species that are not generally present in Mediterranean waters egAtlantic cod [828588] That being said there is evidence that suggests a yield increase of fishpopulations at wind farms as opposed to the simple attraction model previously hypothesized [8586]This is of particular importance for the Mediterranean as levels of fishing are unsustainable and mostfish stocks are in decline [71] The possibility for creating de facto marine protected areas (MPAs) due tofishing restrictions imposed within OWFs is an interesting aspect in the developments of OWFs in theMediterranean Sea It is clear that well protected MPAs in the Mediterranean result in significantlyhigher biomass than those with no or minimal protection [90] although many Mediterranean MPAslack adequate protection [91] Enforcement of fishing restrictions in Mediterranean MPAs is a difficultissue but the benefit associated with designating an area within a series of fixed structures is thatfishing regulations may be easier to enforce Benthic fishermen are less willing to drag their trawlinggear within turbines as they risk entanglement and there is a potential to monitor fishing activity ofstatic and recreational fishermen by using fixed cameras It is worth noting however that displacementof fishing effort is a serious concern for the management of reduced fishing effort regions [92]The production of sound by many fish species for communication during spawning periods means itis also essential for policy makers to identify fish spawning grounds during environmental impactassessments with the aim of restricting OWF construction in these noise-sensitive areas [93]

34 Potential Effects of Mediterranean Benthic Communities

The Mediterranean harbors many important benthic habitats including vermetid reefs coralligenicconcentrations shallow sublittoral rock seamounts deep-sea coral reefs and abyssal plains [9495]The shallow sub-littoral sediment is a particularly valuable habitat for the Mediterranean benthos as itis the preferred habitat of the endemic seagrass Posidonia oceanica listed as a priority natural habitatunder Annex 1 of the EC Habitats Directive (243EEC on the Conservation of Natural Habitatsand of Wild Fauna and Flora) due to its endemism high productivity and provision of ecosystemservices [9697] Favorable substrate conditions for OWF construction throughout Europe is typicallysoft sediment areas and the piling and drilling of foundations and monopile jackets constitutes the mostdirect impact to the marine environment As they favor similar habitats required for the constructionof OWFs Posidonia beds are at risk from direct physical destruction sedimentation and changes inhydrographic regimes Conversely construction may prevent local trawling and therefore decrease theamount of destructive fishing methods that typically reduces Posidonia coverage [98] Any plans forOWFs in the Mediterranean Sea will have to be carefully designed around the distribution of Posidoniato ensure the correct conservation practices for this endemic priority species

Other impacts to soft sediment communities from pre-construction states include changes inregional current regimes causing shifts in macro-benthic assemblages on a localized scale [99100]Studies have shown negative correlations between distance from turbines and grain sizes in the vicinityof turbines (measured from a distance from turbine of 15 m to 200 m) in the Belgian part of the NorthSea which were also positively correlated with increases in organic matter and a shift in species

J Mar Sci Eng 2016 4 18 10 of 17

assemblages The closer to the turbine the soft sediment community samples were taken the greaterthe increase in macrobenthic density and diversity [99]

Although changes in soft-sediment in-fauna are likely to be associated with wind farmconstruction the most direct affect is the addition of hard substratum to the environment Ecosystemshifts occur from changes in the existing soft sediment shifts and the addition of hard substratum ina habitat previously void of available settlement substratum Recruitment and colonization of novelartificial habitats provided by turbine foundations increases the structural complexity and productivityof an environment previously low in in-fauna diversity and density [101ndash110]

Research at an offshore research platform in the German Bight indicated that 35 times moremacro-zoobenthos biomass was associated with the additional hard substratum than the equivalentarea of soft benthic sediment [81] The increase in macro-zoobenthos biomass may appearbeneficial in regard to productivity yet in many cases species assemblages associated with artificialstructures differ from the environment replaced and show lower levels of diversity than natural rockequivalents [81110] Long-term effects of ecosystem shifts are unknown and species assemblagesare influenced by many parameters including material and texture of offshore structures larvalsupply oceanographic conditions temperature salinity and water depth [111] The number ofdefining parameters involved in influencing the spatial and temporal colonization of offshore artificialstructures highlights the need for extensive area-specific research and long-tem in situ experiments tofully understand regional implications of OWFs

With regard to the Mediterranean the limited investigative work into epibenthic colonization hasfocused on concrete artificial reefs [112ndash114] or rock anthropogenic structures [115116] Most studiesareas focus on the Northwestern region of the Mediterranean with the exception of two studies inTurkey and Israel [117118] Only two studies have investigated an offshore steel structure in theMediterranean [117118] Dominating species of epibenthic assemblages varied depending on thelocation and duration of monitoring program which ranged from 11 months to 20 years Most studiescited the initial establishment of Hydozoa Bryozoa and Serpulidae [112117ndash120] In several studiesinitial colonization was followed with the establishment and dominance of the commercially farmedMytilus galloprovincialis [112115119120] However the establishment of mussel beds on artificialstructures in the Mediterranean may be highly localized as several artificial structures showed no suchdominance [117121ndash123] or highly variable results [124] The only long-term data set on a concreteartificial reef (20 years) reported five distinct phases of species assemblage dominance of pioneerspecies mussel dominance mussel regression mussels absence and finally dominance of bryozoanbio-constructions [125] Differences in the material used for offshore structures may have a significanteffect on climax community composition the two offshore steel study sites in the Mediterraneanoffshore steel structures were both dominated by bivalves after 52 and 70 months [119121]

The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonizationof artificial substrata in the Mediterranean by alien species [122127] mean that wind farms may also actas benthic ldquostepping stonesrdquo that facilitate range extension of alien species within the Mediterraneanmarine environment which in turn may potentially reduce the biodiversity of the basin [111128]Due to the apparent locality factor of benthic colonization communites small-scale pilot studies areessential for understanding whether windfarms will proliferate alien species at potential wind farmlocations The use of before-after control-impact studies by policy makers is strongly recommended

35 Potential Effects of Mediterranean Planktonic Communities

The oxygen rich oligotrophic waters of the semi-enclosed Mediterranean produce a lownutrient availability that is however generally intensified along both a west-east and north-southdirection [129] There is nevertheless a high spatial heterogeneity in the distribution of planktonthroughout the Mediterranean Sea due to complex hydrodynamic circulation patterns formingmultiple gyres and upwelling systems [130] Most marine invertebrate and fish species havea planktonic larval stage therefore it is crucial to understand any effects OWFs may have on planktonic

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 6 of 17

farm and avoid the whole rotor swept zone and macro-avoidance being the behavioral alteration ofa flight path due to the presence of a wind farm [46] Macro-avoidance behavior strategies have beenshown in some migrating individuals The common eider Somateria mollissima for example exhibitedavoidance behaviors of a wind turbine at a range of up to 500 m during the day [47] The long-termconsequences of employing avoidance techniques remain unclear Among other parameters realimpacts to population trends of migrating birds will be highly dependent on the specific life historiesof a species expenditure of avoidance strategies energy reserves and weather conditions duringmigratory periods

There are several possible measures to reduce the effects wind farms will have on Mediterraneanavian populations eg shutdown orders and changes to the phototaxis level of structures [4849]However preventative initiatives are much more effective ie ensuring planning and placementof OWFs are not in the vicinity of large population of species that have been identified as high riskwithin the Mediterranean The sensitive species suggested here due to collision or habitat vulnerabilityinclude the lesser black-backed gull the Northern gannet and the red- and black-throated divers whilethe endemic bird species and species whose populations are declining in recent decades (Shearwaters)are identified due to their conservation importance (Table 1) More understanding of the cumulativeeffects of all impacts at all potential development sites is needed Until then all future approaches inregard to OWF spatial planning in the Mediterranean should be of a cautionary nature

32 Potential Effects of Mediterranean Marine Mammals

Marine mammals are often high profile charismatic species and have the potential for highsocio-economic value in their natural habitats [50] It is therefore essential to understand the effectsOWFs will have on Mediterranean populations The Mediterranean Sea is home to both resident andvisiting marine mammals of which most are experiencing a decline in population trends with theexception of visiting humpback whales whose numbers have appeared to increase [1151] At a basinlevel total population numbers are difficult to assess with several species being classified as ldquodatadeficientrdquo by the IUCN red list [20] Nonetheless certain regions have been identified as importanthabitats for marine mammals Monitoring programs show a high percentage of fin whale sightingswithin the Ligurian Sea in comparison with other regions of the Mediterranean Sea [52] The AlboreanSea has been shown to be an important for long-finned pilot whale populations [53] and there is alsoevidence that due to the East-West basin migration of Sperm whales either the Strait of Sicily or theStrait of Messina are critical areas which enable migration [54]

In regard to OWF development several resident marine mammals frequently use the coastalmarine environment earmarked for potential developments including the critically endangeredMediterranean monk seal the common Bottlenose dolphin and visiting Humpback whales [515556]When assessing the combined species density of the resident marine mammals the Gulf of Lion OWFhotspot displays the highest densities of resident marine mammals and as such can be considered asthe most sensitive in regard to OWF development The Gulfs of Hammamet and Gabegraves the Gulf ofSidra and the Nile Delta hotspots appear to support low populations of resident marine mammals(Figure 3)

The distribution of specific species of marine mammals is also of interest to developers This isparticularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently usesthe coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the coast ofTrieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include the thecoast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These regionswill require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise andin particular pile driving during construction has been identified as the biggest impact to marinemammals [58] Increased motorized vessel shipping during the operational phase of wind farms alsoincreases noise levels to the area and so is also identified as an impact however this is not at a level

J Mar Sci Eng 2016 4 18 7 of 17

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the speciespile driven construction has the ability to produce hearing impairment although for most specieshearing reactions are as yet undetermined [60]J Mar Sci Eng 2016 4 18 7 of 17

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Image

adapted from Coll et al [11])

The distribution of specific species of marine mammals is also of interest to developers This is

particularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently

uses the coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the

coast of Trieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include

the the coast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These

regions will require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise and in

particular pile driving during construction has been identified as the biggest impact to marine

mammals [58] Increased motorized vessel shipping during the operational phase of wind farms also

increases noise levels to the area and so is also identified as an impact however this is not at a level

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the species

pile driven construction has the ability to produce hearing impairment although for most species

hearing reactions are as yet undetermined [60]

A study measuring the propagation of sound during the construction phase of an offshore site

in the NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range

of the site and behavior disturbances up to 50 km away [61] With the use of T‐POD porpoise

detectors acoustic monitoring during the construction and into the operational phase of the Nysted

OWF indicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a

reduction in the level of echolocation signals produced by the porpoises [62] A long‐term study (10

years) at the same wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measured

significantly higher acoustic activity inside the farm in comparison with a control site [64] and this

trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggested an

increase in habitat utilization at two operational wind farms (Alpha Ventus and Sheringham Shoal)

[65] The repeated grid‐like movements indicated for the first time successful foraging behavior by

an apex predator within an OWF The apparent differences between probable habitat uses may be

due to local‐scale ecological differences local population habituation of wind farms or differences in

construction type of wind farms [64] Due to critical population levels in the Mediterranean the

observed increases in seal foraging behavior around wind farms may not be relevant to the

Mediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi‐enclosed Mediterranean

also suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In

general noise from wind farms is influenced by water depth wind speed turbine type wind farm

size and substratum type [67] due to the high levels of existing background noise from maritime

traffic in the Mediterranean risks having a cumulative effect in masking communicative abilities of

marine species [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots

of the Gulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels

within the area (up to 140 m vessels∙kmminus2∙dayminus1) thus high levels of background noise can be expected

in these regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levels

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Imageadapted from Coll et al [11])

A study measuring the propagation of sound during the construction phase of an offshore site inthe NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range ofthe site and behavior disturbances up to 50 km away [61] With the use of T-POD porpoise detectorsacoustic monitoring during the construction and into the operational phase of the Nysted OWFindicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a reductionin the level of echolocation signals produced by the porpoises [62] A long-term study (10 years) at thesame wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measuredsignificantly higher acoustic activity inside the farm in comparison with a control site [64] andthis trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggestedan increase in habitat utilization at two operational wind farms (Alpha Ventus and SheringhamShoal) [65] The repeated grid-like movements indicated for the first time successful foraging behaviorby an apex predator within an OWF The apparent differences between probable habitat uses may bedue to local-scale ecological differences local population habituation of wind farms or differencesin construction type of wind farms [64] Due to critical population levels in the Mediterraneanthe observed increases in seal foraging behavior around wind farms may not be relevant to theMediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi-enclosed Mediterraneanalso suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In generalnoise from wind farms is influenced by water depth wind speed turbine type wind farm size andsubstratum type [67] due to the high levels of existing background noise from maritime traffic inthe Mediterranean risks having a cumulative effect in masking communicative abilities of marinespecies [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots of theGulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels withinthe area (up to 140 m vesselsuml kmacute2uml dayacute1) thus high levels of background noise can be expected inthese regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levelsof background noise stress The use of underwater noise propagation models by policy makers willbe required to understand the combined influence of OWF construction operation and maintenanceshipping with current levels of background noise at site-specific locations

J Mar Sci Eng 2016 4 18 8 of 17

J Mar Sci Eng 2016 4 18 8 of 17

of background noise stress The use of underwater noise propagation models by policy makers will

be required to understand the combined influence of OWF construction operation and maintenance

shipping with current levels of background noise at site‐specific locations

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vessel

monitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing‐related activities particularly artisanal

fishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean

8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline of

Mediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro‐magnetic

fields and novel habitat gain Recent studies have shown that the noise generated by pile driving

during the construction phase of OWF farms can generate acute stress responses in juvenile fish

species Although the responses were recorded as acute it is possible that repeated and prolonged

exposure in the wild may lead to a decrease in fitness [72] During the operational stages of OWFs

evidence indicates fish permanently avoid wind turbines only at a range of up to 4 m under high

wind speeds (13 msminus1) and that their ability to communicate and utilize orientation signals is masked

[67] Increased background noise and seabed vibration from operational OWFs and associated marine

traffic will also influence fish detection distances [7374] (Figure 4) Greater numbers of experimental

studies on individual fish species are needed before we can fully comprehend the impact of

anthropogenic noise on fish [75]

Electromagnetic fields occur around intra‐turbine array‐to‐transformer and transformer‐to‐

shore cables The electro‐sensitivity of many marine species is unknown and there is a dearth of peer‐

reviewed information regarding the effects of electro‐magnetic fields Elasmobranchs are thought to

be especially sensitive due to their electro‐sensory organs [76] Several shark and ray species react to

wind farm cables [77] but whether this has any affect at the population level is unknown Magnetic

fields could influence geomagnetic patterns used by some migratory marine species for navigation

[78] and reports also show that electro‐magnetic fields from OWFs may affect fish migration Gill et

al [79] identified eight migratory fish species sensitive to electromagnetic fields including the

European eel Anguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus

albacares Limited in situ data are available about the actual effects on fish which rely on magnetic

fields for migration however several studies in the Baltic Sea have indicated that the swimming

speed of European eels is reduced in the vicinity of underwater electric cables [7880] However due

to the limited availability of empirical studies it is difficult to theorize the extent of the impacts that

electro‐magnetic fields have on Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition of novel

vertical habitat to an area previously void of hard substratum Numerous studies have found greater

abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhua

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vesselmonitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing-related activities particularly artisanalfishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline ofMediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro-magnetic fieldsand novel habitat gain Recent studies have shown that the noise generated by pile driving during theconstruction phase of OWF farms can generate acute stress responses in juvenile fish species Althoughthe responses were recorded as acute it is possible that repeated and prolonged exposure in the wildmay lead to a decrease in fitness [72] During the operational stages of OWFs evidence indicates fishpermanently avoid wind turbines only at a range of up to 4 m under high wind speeds (13 msacute1) andthat their ability to communicate and utilize orientation signals is masked [67] Increased backgroundnoise and seabed vibration from operational OWFs and associated marine traffic will also influencefish detection distances [7374] (Figure 4) Greater numbers of experimental studies on individual fishspecies are needed before we can fully comprehend the impact of anthropogenic noise on fish [75]

Electromagnetic fields occur around intra-turbine array-to-transformer and transformer-to-shorecables The electro-sensitivity of many marine species is unknown and there is a dearth ofpeer-reviewed information regarding the effects of electro-magnetic fields Elasmobranchs are thoughtto be especially sensitive due to their electro-sensory organs [76] Several shark and ray species reactto wind farm cables [77] but whether this has any affect at the population level is unknown Magneticfields could influence geomagnetic patterns used by some migratory marine species for navigation [78]and reports also show that electro-magnetic fields from OWFs may affect fish migration Gill et al [79]identified eight migratory fish species sensitive to electromagnetic fields including the European eelAnguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus albacares Limitedin situ data are available about the actual effects on fish which rely on magnetic fields for migrationhowever several studies in the Baltic Sea have indicated that the swimming speed of European eels isreduced in the vicinity of underwater electric cables [7880] However due to the limited availabilityof empirical studies it is difficult to theorize the extent of the impacts that electro-magnetic fields haveon Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition ofnovel vertical habitat to an area previously void of hard substratum Numerous studies have foundgreater abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhuapouting Trisopterus luscus and several species of gobies [81ndash83] Currently most empirically measuredeffects due to operational wind turbines are temporally limited and not at the scale of OWFs [60]Several studies have implied that the new habitat provides increased foraging for both primaryand secondary food resources and protection grounds from currents [84] There is much discussion

J Mar Sci Eng 2016 4 18 9 of 17

between ecologists over whether changes in species biomass will be due to attraction or production [85]Stomach content analysis and energy profiling have shown that OWFs are suitable feeding groundsfor both Atlantic cod and pouting species [8687] indicating that there is extra biomass available at thesites Juvenile recruitment of Atlantic cod has also been observed at wind farms in the Belgium partof the North Sea [87] Changes in prey densities may also be masked by predation rates [6588] andwill potentially strengthen predator avoidance behaviors like diel migration further complicating therelationship between attraction-production dynamics [77] While the mechanics of fish abundanceat OWFs is not yet fully understood and requires additional analysis it is becoming increasinglyobvious that any ecological benefits will only be attained if fishing practices are banned within thewind farms [89]

For Mediterranean fish species it is difficult to state the effects based on the findings of NorthernEuropean studies as there is a limited availability of information and the majority of existingmonitoring programs focus on species that are not generally present in Mediterranean waters egAtlantic cod [828588] That being said there is evidence that suggests a yield increase of fishpopulations at wind farms as opposed to the simple attraction model previously hypothesized [8586]This is of particular importance for the Mediterranean as levels of fishing are unsustainable and mostfish stocks are in decline [71] The possibility for creating de facto marine protected areas (MPAs) due tofishing restrictions imposed within OWFs is an interesting aspect in the developments of OWFs in theMediterranean Sea It is clear that well protected MPAs in the Mediterranean result in significantlyhigher biomass than those with no or minimal protection [90] although many Mediterranean MPAslack adequate protection [91] Enforcement of fishing restrictions in Mediterranean MPAs is a difficultissue but the benefit associated with designating an area within a series of fixed structures is thatfishing regulations may be easier to enforce Benthic fishermen are less willing to drag their trawlinggear within turbines as they risk entanglement and there is a potential to monitor fishing activity ofstatic and recreational fishermen by using fixed cameras It is worth noting however that displacementof fishing effort is a serious concern for the management of reduced fishing effort regions [92]The production of sound by many fish species for communication during spawning periods means itis also essential for policy makers to identify fish spawning grounds during environmental impactassessments with the aim of restricting OWF construction in these noise-sensitive areas [93]

34 Potential Effects of Mediterranean Benthic Communities

The Mediterranean harbors many important benthic habitats including vermetid reefs coralligenicconcentrations shallow sublittoral rock seamounts deep-sea coral reefs and abyssal plains [9495]The shallow sub-littoral sediment is a particularly valuable habitat for the Mediterranean benthos as itis the preferred habitat of the endemic seagrass Posidonia oceanica listed as a priority natural habitatunder Annex 1 of the EC Habitats Directive (243EEC on the Conservation of Natural Habitatsand of Wild Fauna and Flora) due to its endemism high productivity and provision of ecosystemservices [9697] Favorable substrate conditions for OWF construction throughout Europe is typicallysoft sediment areas and the piling and drilling of foundations and monopile jackets constitutes the mostdirect impact to the marine environment As they favor similar habitats required for the constructionof OWFs Posidonia beds are at risk from direct physical destruction sedimentation and changes inhydrographic regimes Conversely construction may prevent local trawling and therefore decrease theamount of destructive fishing methods that typically reduces Posidonia coverage [98] Any plans forOWFs in the Mediterranean Sea will have to be carefully designed around the distribution of Posidoniato ensure the correct conservation practices for this endemic priority species

Other impacts to soft sediment communities from pre-construction states include changes inregional current regimes causing shifts in macro-benthic assemblages on a localized scale [99100]Studies have shown negative correlations between distance from turbines and grain sizes in the vicinityof turbines (measured from a distance from turbine of 15 m to 200 m) in the Belgian part of the NorthSea which were also positively correlated with increases in organic matter and a shift in species

J Mar Sci Eng 2016 4 18 10 of 17

assemblages The closer to the turbine the soft sediment community samples were taken the greaterthe increase in macrobenthic density and diversity [99]

Although changes in soft-sediment in-fauna are likely to be associated with wind farmconstruction the most direct affect is the addition of hard substratum to the environment Ecosystemshifts occur from changes in the existing soft sediment shifts and the addition of hard substratum ina habitat previously void of available settlement substratum Recruitment and colonization of novelartificial habitats provided by turbine foundations increases the structural complexity and productivityof an environment previously low in in-fauna diversity and density [101ndash110]

Research at an offshore research platform in the German Bight indicated that 35 times moremacro-zoobenthos biomass was associated with the additional hard substratum than the equivalentarea of soft benthic sediment [81] The increase in macro-zoobenthos biomass may appearbeneficial in regard to productivity yet in many cases species assemblages associated with artificialstructures differ from the environment replaced and show lower levels of diversity than natural rockequivalents [81110] Long-term effects of ecosystem shifts are unknown and species assemblagesare influenced by many parameters including material and texture of offshore structures larvalsupply oceanographic conditions temperature salinity and water depth [111] The number ofdefining parameters involved in influencing the spatial and temporal colonization of offshore artificialstructures highlights the need for extensive area-specific research and long-tem in situ experiments tofully understand regional implications of OWFs

With regard to the Mediterranean the limited investigative work into epibenthic colonization hasfocused on concrete artificial reefs [112ndash114] or rock anthropogenic structures [115116] Most studiesareas focus on the Northwestern region of the Mediterranean with the exception of two studies inTurkey and Israel [117118] Only two studies have investigated an offshore steel structure in theMediterranean [117118] Dominating species of epibenthic assemblages varied depending on thelocation and duration of monitoring program which ranged from 11 months to 20 years Most studiescited the initial establishment of Hydozoa Bryozoa and Serpulidae [112117ndash120] In several studiesinitial colonization was followed with the establishment and dominance of the commercially farmedMytilus galloprovincialis [112115119120] However the establishment of mussel beds on artificialstructures in the Mediterranean may be highly localized as several artificial structures showed no suchdominance [117121ndash123] or highly variable results [124] The only long-term data set on a concreteartificial reef (20 years) reported five distinct phases of species assemblage dominance of pioneerspecies mussel dominance mussel regression mussels absence and finally dominance of bryozoanbio-constructions [125] Differences in the material used for offshore structures may have a significanteffect on climax community composition the two offshore steel study sites in the Mediterraneanoffshore steel structures were both dominated by bivalves after 52 and 70 months [119121]

The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonizationof artificial substrata in the Mediterranean by alien species [122127] mean that wind farms may also actas benthic ldquostepping stonesrdquo that facilitate range extension of alien species within the Mediterraneanmarine environment which in turn may potentially reduce the biodiversity of the basin [111128]Due to the apparent locality factor of benthic colonization communites small-scale pilot studies areessential for understanding whether windfarms will proliferate alien species at potential wind farmlocations The use of before-after control-impact studies by policy makers is strongly recommended

35 Potential Effects of Mediterranean Planktonic Communities

The oxygen rich oligotrophic waters of the semi-enclosed Mediterranean produce a lownutrient availability that is however generally intensified along both a west-east and north-southdirection [129] There is nevertheless a high spatial heterogeneity in the distribution of planktonthroughout the Mediterranean Sea due to complex hydrodynamic circulation patterns formingmultiple gyres and upwelling systems [130] Most marine invertebrate and fish species havea planktonic larval stage therefore it is crucial to understand any effects OWFs may have on planktonic

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 7 of 17

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the speciespile driven construction has the ability to produce hearing impairment although for most specieshearing reactions are as yet undetermined [60]J Mar Sci Eng 2016 4 18 7 of 17

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Image

adapted from Coll et al [11])

The distribution of specific species of marine mammals is also of interest to developers This is

particularly true within the Northern Adriatic OWF hotspot The Mediterranean monk frequently

uses the coast of Croatia (Figure 1B [57]) and the Bottlenose dolphins regularly sighted from the

coast of Trieste and Kvarneric (Figure 1B [55]) Other important areas for individual species include

the the coast of Senigallia and the Gulf of Gabes for the Humpback whale (Figure 1AC) [51] These

regions will require particular attention during spatial planning stages of developers

Through monitoring programs conducted in the Northern European seas marine noise and in

particular pile driving during construction has been identified as the biggest impact to marine

mammals [58] Increased motorized vessel shipping during the operational phase of wind farms also

increases noise levels to the area and so is also identified as an impact however this is not at a level

expected to significantly affect marine mammals [59] Depending on the hearing ranges of the species

pile driven construction has the ability to produce hearing impairment although for most species

hearing reactions are as yet undetermined [60]

A study measuring the propagation of sound during the construction phase of an offshore site

in the NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range

of the site and behavior disturbances up to 50 km away [61] With the use of T‐POD porpoise

detectors acoustic monitoring during the construction and into the operational phase of the Nysted

OWF indicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a

reduction in the level of echolocation signals produced by the porpoises [62] A long‐term study (10

years) at the same wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measured

significantly higher acoustic activity inside the farm in comparison with a control site [64] and this

trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggested an

increase in habitat utilization at two operational wind farms (Alpha Ventus and Sheringham Shoal)

[65] The repeated grid‐like movements indicated for the first time successful foraging behavior by

an apex predator within an OWF The apparent differences between probable habitat uses may be

due to local‐scale ecological differences local population habituation of wind farms or differences in

construction type of wind farms [64] Due to critical population levels in the Mediterranean the

observed increases in seal foraging behavior around wind farms may not be relevant to the

Mediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi‐enclosed Mediterranean

also suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In

general noise from wind farms is influenced by water depth wind speed turbine type wind farm

size and substratum type [67] due to the high levels of existing background noise from maritime

traffic in the Mediterranean risks having a cumulative effect in masking communicative abilities of

marine species [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots

of the Gulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels

within the area (up to 140 m vessels∙kmminus2∙dayminus1) thus high levels of background noise can be expected

in these regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levels

Figure 3 Species density of all resident marine mammals (n = 9) with overlay of OWF hotspots (Imageadapted from Coll et al [11])

A study measuring the propagation of sound during the construction phase of an offshore site inthe NE of Scotland implied Bottlenose dolphins would suffer auditory injury within a 100 m range ofthe site and behavior disturbances up to 50 km away [61] With the use of T-POD porpoise detectorsacoustic monitoring during the construction and into the operational phase of the Nysted OWFindicated a possible change in habitat use by the harbor porpoise (Phocoena phocoena) with a reductionin the level of echolocation signals produced by the porpoises [62] A long-term study (10 years) at thesame wind farm also showed a decline from baseline levels of echolocation signals [63]

A similar study at the Dutch wind farm Egmond aan Zee after construction measuredsignificantly higher acoustic activity inside the farm in comparison with a control site [64] andthis trend was mirrored in a recent study of harbor seal (Phoca vitulina) foraging which suggestedan increase in habitat utilization at two operational wind farms (Alpha Ventus and SheringhamShoal) [65] The repeated grid-like movements indicated for the first time successful foraging behaviorby an apex predator within an OWF The apparent differences between probable habitat uses may bedue to local-scale ecological differences local population habituation of wind farms or differencesin construction type of wind farms [64] Due to critical population levels in the Mediterraneanthe observed increases in seal foraging behavior around wind farms may not be relevant to theMediterranean monk seal [5665]

In regard to the impacts of noise levels in the Mediterranean the semi-enclosed Mediterraneanalso suffers from some of the highest volume of shipping routes in the world [66] (Figure 4) In generalnoise from wind farms is influenced by water depth wind speed turbine type wind farm size andsubstratum type [67] due to the high levels of existing background noise from maritime traffic inthe Mediterranean risks having a cumulative effect in masking communicative abilities of marinespecies [68] When assessing the spatial density of traffic routes from 2013 the OWF hotspots of theGulf of Lion the North Adriatic Sea and the Nile Delta show an already high density of vessels withinthe area (up to 140 m vesselsuml kmacute2uml dayacute1) thus high levels of background noise can be expected inthese regions The Gulf of Hammamet and Gabegraves and the Gulf of Sidra suggest much lower levelsof background noise stress The use of underwater noise propagation models by policy makers willbe required to understand the combined influence of OWF construction operation and maintenanceshipping with current levels of background noise at site-specific locations

J Mar Sci Eng 2016 4 18 8 of 17

J Mar Sci Eng 2016 4 18 8 of 17

of background noise stress The use of underwater noise propagation models by policy makers will

be required to understand the combined influence of OWF construction operation and maintenance

shipping with current levels of background noise at site‐specific locations

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vessel

monitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing‐related activities particularly artisanal

fishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean

8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline of

Mediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro‐magnetic

fields and novel habitat gain Recent studies have shown that the noise generated by pile driving

during the construction phase of OWF farms can generate acute stress responses in juvenile fish

species Although the responses were recorded as acute it is possible that repeated and prolonged

exposure in the wild may lead to a decrease in fitness [72] During the operational stages of OWFs

evidence indicates fish permanently avoid wind turbines only at a range of up to 4 m under high

wind speeds (13 msminus1) and that their ability to communicate and utilize orientation signals is masked

[67] Increased background noise and seabed vibration from operational OWFs and associated marine

traffic will also influence fish detection distances [7374] (Figure 4) Greater numbers of experimental

studies on individual fish species are needed before we can fully comprehend the impact of

anthropogenic noise on fish [75]

Electromagnetic fields occur around intra‐turbine array‐to‐transformer and transformer‐to‐

shore cables The electro‐sensitivity of many marine species is unknown and there is a dearth of peer‐

reviewed information regarding the effects of electro‐magnetic fields Elasmobranchs are thought to

be especially sensitive due to their electro‐sensory organs [76] Several shark and ray species react to

wind farm cables [77] but whether this has any affect at the population level is unknown Magnetic

fields could influence geomagnetic patterns used by some migratory marine species for navigation

[78] and reports also show that electro‐magnetic fields from OWFs may affect fish migration Gill et

al [79] identified eight migratory fish species sensitive to electromagnetic fields including the

European eel Anguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus

albacares Limited in situ data are available about the actual effects on fish which rely on magnetic

fields for migration however several studies in the Baltic Sea have indicated that the swimming

speed of European eels is reduced in the vicinity of underwater electric cables [7880] However due

to the limited availability of empirical studies it is difficult to theorize the extent of the impacts that

electro‐magnetic fields have on Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition of novel

vertical habitat to an area previously void of hard substratum Numerous studies have found greater

abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhua

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vesselmonitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing-related activities particularly artisanalfishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline ofMediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro-magnetic fieldsand novel habitat gain Recent studies have shown that the noise generated by pile driving during theconstruction phase of OWF farms can generate acute stress responses in juvenile fish species Althoughthe responses were recorded as acute it is possible that repeated and prolonged exposure in the wildmay lead to a decrease in fitness [72] During the operational stages of OWFs evidence indicates fishpermanently avoid wind turbines only at a range of up to 4 m under high wind speeds (13 msacute1) andthat their ability to communicate and utilize orientation signals is masked [67] Increased backgroundnoise and seabed vibration from operational OWFs and associated marine traffic will also influencefish detection distances [7374] (Figure 4) Greater numbers of experimental studies on individual fishspecies are needed before we can fully comprehend the impact of anthropogenic noise on fish [75]

Electromagnetic fields occur around intra-turbine array-to-transformer and transformer-to-shorecables The electro-sensitivity of many marine species is unknown and there is a dearth ofpeer-reviewed information regarding the effects of electro-magnetic fields Elasmobranchs are thoughtto be especially sensitive due to their electro-sensory organs [76] Several shark and ray species reactto wind farm cables [77] but whether this has any affect at the population level is unknown Magneticfields could influence geomagnetic patterns used by some migratory marine species for navigation [78]and reports also show that electro-magnetic fields from OWFs may affect fish migration Gill et al [79]identified eight migratory fish species sensitive to electromagnetic fields including the European eelAnguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus albacares Limitedin situ data are available about the actual effects on fish which rely on magnetic fields for migrationhowever several studies in the Baltic Sea have indicated that the swimming speed of European eels isreduced in the vicinity of underwater electric cables [7880] However due to the limited availabilityof empirical studies it is difficult to theorize the extent of the impacts that electro-magnetic fields haveon Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition ofnovel vertical habitat to an area previously void of hard substratum Numerous studies have foundgreater abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhuapouting Trisopterus luscus and several species of gobies [81ndash83] Currently most empirically measuredeffects due to operational wind turbines are temporally limited and not at the scale of OWFs [60]Several studies have implied that the new habitat provides increased foraging for both primaryand secondary food resources and protection grounds from currents [84] There is much discussion

J Mar Sci Eng 2016 4 18 9 of 17

between ecologists over whether changes in species biomass will be due to attraction or production [85]Stomach content analysis and energy profiling have shown that OWFs are suitable feeding groundsfor both Atlantic cod and pouting species [8687] indicating that there is extra biomass available at thesites Juvenile recruitment of Atlantic cod has also been observed at wind farms in the Belgium partof the North Sea [87] Changes in prey densities may also be masked by predation rates [6588] andwill potentially strengthen predator avoidance behaviors like diel migration further complicating therelationship between attraction-production dynamics [77] While the mechanics of fish abundanceat OWFs is not yet fully understood and requires additional analysis it is becoming increasinglyobvious that any ecological benefits will only be attained if fishing practices are banned within thewind farms [89]

For Mediterranean fish species it is difficult to state the effects based on the findings of NorthernEuropean studies as there is a limited availability of information and the majority of existingmonitoring programs focus on species that are not generally present in Mediterranean waters egAtlantic cod [828588] That being said there is evidence that suggests a yield increase of fishpopulations at wind farms as opposed to the simple attraction model previously hypothesized [8586]This is of particular importance for the Mediterranean as levels of fishing are unsustainable and mostfish stocks are in decline [71] The possibility for creating de facto marine protected areas (MPAs) due tofishing restrictions imposed within OWFs is an interesting aspect in the developments of OWFs in theMediterranean Sea It is clear that well protected MPAs in the Mediterranean result in significantlyhigher biomass than those with no or minimal protection [90] although many Mediterranean MPAslack adequate protection [91] Enforcement of fishing restrictions in Mediterranean MPAs is a difficultissue but the benefit associated with designating an area within a series of fixed structures is thatfishing regulations may be easier to enforce Benthic fishermen are less willing to drag their trawlinggear within turbines as they risk entanglement and there is a potential to monitor fishing activity ofstatic and recreational fishermen by using fixed cameras It is worth noting however that displacementof fishing effort is a serious concern for the management of reduced fishing effort regions [92]The production of sound by many fish species for communication during spawning periods means itis also essential for policy makers to identify fish spawning grounds during environmental impactassessments with the aim of restricting OWF construction in these noise-sensitive areas [93]

34 Potential Effects of Mediterranean Benthic Communities

The Mediterranean harbors many important benthic habitats including vermetid reefs coralligenicconcentrations shallow sublittoral rock seamounts deep-sea coral reefs and abyssal plains [9495]The shallow sub-littoral sediment is a particularly valuable habitat for the Mediterranean benthos as itis the preferred habitat of the endemic seagrass Posidonia oceanica listed as a priority natural habitatunder Annex 1 of the EC Habitats Directive (243EEC on the Conservation of Natural Habitatsand of Wild Fauna and Flora) due to its endemism high productivity and provision of ecosystemservices [9697] Favorable substrate conditions for OWF construction throughout Europe is typicallysoft sediment areas and the piling and drilling of foundations and monopile jackets constitutes the mostdirect impact to the marine environment As they favor similar habitats required for the constructionof OWFs Posidonia beds are at risk from direct physical destruction sedimentation and changes inhydrographic regimes Conversely construction may prevent local trawling and therefore decrease theamount of destructive fishing methods that typically reduces Posidonia coverage [98] Any plans forOWFs in the Mediterranean Sea will have to be carefully designed around the distribution of Posidoniato ensure the correct conservation practices for this endemic priority species

Other impacts to soft sediment communities from pre-construction states include changes inregional current regimes causing shifts in macro-benthic assemblages on a localized scale [99100]Studies have shown negative correlations between distance from turbines and grain sizes in the vicinityof turbines (measured from a distance from turbine of 15 m to 200 m) in the Belgian part of the NorthSea which were also positively correlated with increases in organic matter and a shift in species

J Mar Sci Eng 2016 4 18 10 of 17

assemblages The closer to the turbine the soft sediment community samples were taken the greaterthe increase in macrobenthic density and diversity [99]

Although changes in soft-sediment in-fauna are likely to be associated with wind farmconstruction the most direct affect is the addition of hard substratum to the environment Ecosystemshifts occur from changes in the existing soft sediment shifts and the addition of hard substratum ina habitat previously void of available settlement substratum Recruitment and colonization of novelartificial habitats provided by turbine foundations increases the structural complexity and productivityof an environment previously low in in-fauna diversity and density [101ndash110]

Research at an offshore research platform in the German Bight indicated that 35 times moremacro-zoobenthos biomass was associated with the additional hard substratum than the equivalentarea of soft benthic sediment [81] The increase in macro-zoobenthos biomass may appearbeneficial in regard to productivity yet in many cases species assemblages associated with artificialstructures differ from the environment replaced and show lower levels of diversity than natural rockequivalents [81110] Long-term effects of ecosystem shifts are unknown and species assemblagesare influenced by many parameters including material and texture of offshore structures larvalsupply oceanographic conditions temperature salinity and water depth [111] The number ofdefining parameters involved in influencing the spatial and temporal colonization of offshore artificialstructures highlights the need for extensive area-specific research and long-tem in situ experiments tofully understand regional implications of OWFs

With regard to the Mediterranean the limited investigative work into epibenthic colonization hasfocused on concrete artificial reefs [112ndash114] or rock anthropogenic structures [115116] Most studiesareas focus on the Northwestern region of the Mediterranean with the exception of two studies inTurkey and Israel [117118] Only two studies have investigated an offshore steel structure in theMediterranean [117118] Dominating species of epibenthic assemblages varied depending on thelocation and duration of monitoring program which ranged from 11 months to 20 years Most studiescited the initial establishment of Hydozoa Bryozoa and Serpulidae [112117ndash120] In several studiesinitial colonization was followed with the establishment and dominance of the commercially farmedMytilus galloprovincialis [112115119120] However the establishment of mussel beds on artificialstructures in the Mediterranean may be highly localized as several artificial structures showed no suchdominance [117121ndash123] or highly variable results [124] The only long-term data set on a concreteartificial reef (20 years) reported five distinct phases of species assemblage dominance of pioneerspecies mussel dominance mussel regression mussels absence and finally dominance of bryozoanbio-constructions [125] Differences in the material used for offshore structures may have a significanteffect on climax community composition the two offshore steel study sites in the Mediterraneanoffshore steel structures were both dominated by bivalves after 52 and 70 months [119121]

The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonizationof artificial substrata in the Mediterranean by alien species [122127] mean that wind farms may also actas benthic ldquostepping stonesrdquo that facilitate range extension of alien species within the Mediterraneanmarine environment which in turn may potentially reduce the biodiversity of the basin [111128]Due to the apparent locality factor of benthic colonization communites small-scale pilot studies areessential for understanding whether windfarms will proliferate alien species at potential wind farmlocations The use of before-after control-impact studies by policy makers is strongly recommended

35 Potential Effects of Mediterranean Planktonic Communities

The oxygen rich oligotrophic waters of the semi-enclosed Mediterranean produce a lownutrient availability that is however generally intensified along both a west-east and north-southdirection [129] There is nevertheless a high spatial heterogeneity in the distribution of planktonthroughout the Mediterranean Sea due to complex hydrodynamic circulation patterns formingmultiple gyres and upwelling systems [130] Most marine invertebrate and fish species havea planktonic larval stage therefore it is crucial to understand any effects OWFs may have on planktonic

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 8 of 17

J Mar Sci Eng 2016 4 18 8 of 17

of background noise stress The use of underwater noise propagation models by policy makers will

be required to understand the combined influence of OWF construction operation and maintenance

shipping with current levels of background noise at site‐specific locations

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vessel

monitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing‐related activities particularly artisanal

fishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean

8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline of

Mediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro‐magnetic

fields and novel habitat gain Recent studies have shown that the noise generated by pile driving

during the construction phase of OWF farms can generate acute stress responses in juvenile fish

species Although the responses were recorded as acute it is possible that repeated and prolonged

exposure in the wild may lead to a decrease in fitness [72] During the operational stages of OWFs

evidence indicates fish permanently avoid wind turbines only at a range of up to 4 m under high

wind speeds (13 msminus1) and that their ability to communicate and utilize orientation signals is masked

[67] Increased background noise and seabed vibration from operational OWFs and associated marine

traffic will also influence fish detection distances [7374] (Figure 4) Greater numbers of experimental

studies on individual fish species are needed before we can fully comprehend the impact of

anthropogenic noise on fish [75]

Electromagnetic fields occur around intra‐turbine array‐to‐transformer and transformer‐to‐

shore cables The electro‐sensitivity of many marine species is unknown and there is a dearth of peer‐

reviewed information regarding the effects of electro‐magnetic fields Elasmobranchs are thought to

be especially sensitive due to their electro‐sensory organs [76] Several shark and ray species react to

wind farm cables [77] but whether this has any affect at the population level is unknown Magnetic

fields could influence geomagnetic patterns used by some migratory marine species for navigation

[78] and reports also show that electro‐magnetic fields from OWFs may affect fish migration Gill et

al [79] identified eight migratory fish species sensitive to electromagnetic fields including the

European eel Anguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus

albacares Limited in situ data are available about the actual effects on fish which rely on magnetic

fields for migration however several studies in the Baltic Sea have indicated that the swimming

speed of European eels is reduced in the vicinity of underwater electric cables [7880] However due

to the limited availability of empirical studies it is difficult to theorize the extent of the impacts that

electro‐magnetic fields have on Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition of novel

vertical habitat to an area previously void of hard substratum Numerous studies have found greater

abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhua

Figure 4 Combined density of 2013 maritime routes of all commercial vessels obtained via AIS vesselmonitoring with overlay of OWF hotspots (source wwwmarinetrafficcom)

33 Potential Effects on Mediterranean Fish Communities

Mediterranean coastal communities depend on fishing-related activities particularly artisanalfishing throughout the basin [69] Of the 513 species and 6 subspecies of fish in the Mediterranean8 are currently classified as threatened by the IUCN [70] and there has been an alarming decline ofMediterranean fish stocks with the largest declines in demersal fish stocks [71]

The principal impacts to fish populations caused by wind farms are noise electro-magnetic fieldsand novel habitat gain Recent studies have shown that the noise generated by pile driving during theconstruction phase of OWF farms can generate acute stress responses in juvenile fish species Althoughthe responses were recorded as acute it is possible that repeated and prolonged exposure in the wildmay lead to a decrease in fitness [72] During the operational stages of OWFs evidence indicates fishpermanently avoid wind turbines only at a range of up to 4 m under high wind speeds (13 msacute1) andthat their ability to communicate and utilize orientation signals is masked [67] Increased backgroundnoise and seabed vibration from operational OWFs and associated marine traffic will also influencefish detection distances [7374] (Figure 4) Greater numbers of experimental studies on individual fishspecies are needed before we can fully comprehend the impact of anthropogenic noise on fish [75]

Electromagnetic fields occur around intra-turbine array-to-transformer and transformer-to-shorecables The electro-sensitivity of many marine species is unknown and there is a dearth ofpeer-reviewed information regarding the effects of electro-magnetic fields Elasmobranchs are thoughtto be especially sensitive due to their electro-sensory organs [76] Several shark and ray species reactto wind farm cables [77] but whether this has any affect at the population level is unknown Magneticfields could influence geomagnetic patterns used by some migratory marine species for navigation [78]and reports also show that electro-magnetic fields from OWFs may affect fish migration Gill et al [79]identified eight migratory fish species sensitive to electromagnetic fields including the European eelAnguilla anguilla the Atlantic salmon Salmo salar and the Yellowfin tuna Thunnus albacares Limitedin situ data are available about the actual effects on fish which rely on magnetic fields for migrationhowever several studies in the Baltic Sea have indicated that the swimming speed of European eels isreduced in the vicinity of underwater electric cables [7880] However due to the limited availabilityof empirical studies it is difficult to theorize the extent of the impacts that electro-magnetic fields haveon Mediterranean marine species and their fecundity

The most direct influence on fisheries due to the presence of OWFs is likely the addition ofnovel vertical habitat to an area previously void of hard substratum Numerous studies have foundgreater abundances in fish around OWFs than in surrounding areas such as Atlantic cod Gadus morhuapouting Trisopterus luscus and several species of gobies [81ndash83] Currently most empirically measuredeffects due to operational wind turbines are temporally limited and not at the scale of OWFs [60]Several studies have implied that the new habitat provides increased foraging for both primaryand secondary food resources and protection grounds from currents [84] There is much discussion

J Mar Sci Eng 2016 4 18 9 of 17

between ecologists over whether changes in species biomass will be due to attraction or production [85]Stomach content analysis and energy profiling have shown that OWFs are suitable feeding groundsfor both Atlantic cod and pouting species [8687] indicating that there is extra biomass available at thesites Juvenile recruitment of Atlantic cod has also been observed at wind farms in the Belgium partof the North Sea [87] Changes in prey densities may also be masked by predation rates [6588] andwill potentially strengthen predator avoidance behaviors like diel migration further complicating therelationship between attraction-production dynamics [77] While the mechanics of fish abundanceat OWFs is not yet fully understood and requires additional analysis it is becoming increasinglyobvious that any ecological benefits will only be attained if fishing practices are banned within thewind farms [89]

For Mediterranean fish species it is difficult to state the effects based on the findings of NorthernEuropean studies as there is a limited availability of information and the majority of existingmonitoring programs focus on species that are not generally present in Mediterranean waters egAtlantic cod [828588] That being said there is evidence that suggests a yield increase of fishpopulations at wind farms as opposed to the simple attraction model previously hypothesized [8586]This is of particular importance for the Mediterranean as levels of fishing are unsustainable and mostfish stocks are in decline [71] The possibility for creating de facto marine protected areas (MPAs) due tofishing restrictions imposed within OWFs is an interesting aspect in the developments of OWFs in theMediterranean Sea It is clear that well protected MPAs in the Mediterranean result in significantlyhigher biomass than those with no or minimal protection [90] although many Mediterranean MPAslack adequate protection [91] Enforcement of fishing restrictions in Mediterranean MPAs is a difficultissue but the benefit associated with designating an area within a series of fixed structures is thatfishing regulations may be easier to enforce Benthic fishermen are less willing to drag their trawlinggear within turbines as they risk entanglement and there is a potential to monitor fishing activity ofstatic and recreational fishermen by using fixed cameras It is worth noting however that displacementof fishing effort is a serious concern for the management of reduced fishing effort regions [92]The production of sound by many fish species for communication during spawning periods means itis also essential for policy makers to identify fish spawning grounds during environmental impactassessments with the aim of restricting OWF construction in these noise-sensitive areas [93]

34 Potential Effects of Mediterranean Benthic Communities

The Mediterranean harbors many important benthic habitats including vermetid reefs coralligenicconcentrations shallow sublittoral rock seamounts deep-sea coral reefs and abyssal plains [9495]The shallow sub-littoral sediment is a particularly valuable habitat for the Mediterranean benthos as itis the preferred habitat of the endemic seagrass Posidonia oceanica listed as a priority natural habitatunder Annex 1 of the EC Habitats Directive (243EEC on the Conservation of Natural Habitatsand of Wild Fauna and Flora) due to its endemism high productivity and provision of ecosystemservices [9697] Favorable substrate conditions for OWF construction throughout Europe is typicallysoft sediment areas and the piling and drilling of foundations and monopile jackets constitutes the mostdirect impact to the marine environment As they favor similar habitats required for the constructionof OWFs Posidonia beds are at risk from direct physical destruction sedimentation and changes inhydrographic regimes Conversely construction may prevent local trawling and therefore decrease theamount of destructive fishing methods that typically reduces Posidonia coverage [98] Any plans forOWFs in the Mediterranean Sea will have to be carefully designed around the distribution of Posidoniato ensure the correct conservation practices for this endemic priority species

Other impacts to soft sediment communities from pre-construction states include changes inregional current regimes causing shifts in macro-benthic assemblages on a localized scale [99100]Studies have shown negative correlations between distance from turbines and grain sizes in the vicinityof turbines (measured from a distance from turbine of 15 m to 200 m) in the Belgian part of the NorthSea which were also positively correlated with increases in organic matter and a shift in species

J Mar Sci Eng 2016 4 18 10 of 17

assemblages The closer to the turbine the soft sediment community samples were taken the greaterthe increase in macrobenthic density and diversity [99]

Although changes in soft-sediment in-fauna are likely to be associated with wind farmconstruction the most direct affect is the addition of hard substratum to the environment Ecosystemshifts occur from changes in the existing soft sediment shifts and the addition of hard substratum ina habitat previously void of available settlement substratum Recruitment and colonization of novelartificial habitats provided by turbine foundations increases the structural complexity and productivityof an environment previously low in in-fauna diversity and density [101ndash110]

Research at an offshore research platform in the German Bight indicated that 35 times moremacro-zoobenthos biomass was associated with the additional hard substratum than the equivalentarea of soft benthic sediment [81] The increase in macro-zoobenthos biomass may appearbeneficial in regard to productivity yet in many cases species assemblages associated with artificialstructures differ from the environment replaced and show lower levels of diversity than natural rockequivalents [81110] Long-term effects of ecosystem shifts are unknown and species assemblagesare influenced by many parameters including material and texture of offshore structures larvalsupply oceanographic conditions temperature salinity and water depth [111] The number ofdefining parameters involved in influencing the spatial and temporal colonization of offshore artificialstructures highlights the need for extensive area-specific research and long-tem in situ experiments tofully understand regional implications of OWFs

With regard to the Mediterranean the limited investigative work into epibenthic colonization hasfocused on concrete artificial reefs [112ndash114] or rock anthropogenic structures [115116] Most studiesareas focus on the Northwestern region of the Mediterranean with the exception of two studies inTurkey and Israel [117118] Only two studies have investigated an offshore steel structure in theMediterranean [117118] Dominating species of epibenthic assemblages varied depending on thelocation and duration of monitoring program which ranged from 11 months to 20 years Most studiescited the initial establishment of Hydozoa Bryozoa and Serpulidae [112117ndash120] In several studiesinitial colonization was followed with the establishment and dominance of the commercially farmedMytilus galloprovincialis [112115119120] However the establishment of mussel beds on artificialstructures in the Mediterranean may be highly localized as several artificial structures showed no suchdominance [117121ndash123] or highly variable results [124] The only long-term data set on a concreteartificial reef (20 years) reported five distinct phases of species assemblage dominance of pioneerspecies mussel dominance mussel regression mussels absence and finally dominance of bryozoanbio-constructions [125] Differences in the material used for offshore structures may have a significanteffect on climax community composition the two offshore steel study sites in the Mediterraneanoffshore steel structures were both dominated by bivalves after 52 and 70 months [119121]

The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonizationof artificial substrata in the Mediterranean by alien species [122127] mean that wind farms may also actas benthic ldquostepping stonesrdquo that facilitate range extension of alien species within the Mediterraneanmarine environment which in turn may potentially reduce the biodiversity of the basin [111128]Due to the apparent locality factor of benthic colonization communites small-scale pilot studies areessential for understanding whether windfarms will proliferate alien species at potential wind farmlocations The use of before-after control-impact studies by policy makers is strongly recommended

35 Potential Effects of Mediterranean Planktonic Communities

The oxygen rich oligotrophic waters of the semi-enclosed Mediterranean produce a lownutrient availability that is however generally intensified along both a west-east and north-southdirection [129] There is nevertheless a high spatial heterogeneity in the distribution of planktonthroughout the Mediterranean Sea due to complex hydrodynamic circulation patterns formingmultiple gyres and upwelling systems [130] Most marine invertebrate and fish species havea planktonic larval stage therefore it is crucial to understand any effects OWFs may have on planktonic

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 9 of 17

between ecologists over whether changes in species biomass will be due to attraction or production [85]Stomach content analysis and energy profiling have shown that OWFs are suitable feeding groundsfor both Atlantic cod and pouting species [8687] indicating that there is extra biomass available at thesites Juvenile recruitment of Atlantic cod has also been observed at wind farms in the Belgium partof the North Sea [87] Changes in prey densities may also be masked by predation rates [6588] andwill potentially strengthen predator avoidance behaviors like diel migration further complicating therelationship between attraction-production dynamics [77] While the mechanics of fish abundanceat OWFs is not yet fully understood and requires additional analysis it is becoming increasinglyobvious that any ecological benefits will only be attained if fishing practices are banned within thewind farms [89]

For Mediterranean fish species it is difficult to state the effects based on the findings of NorthernEuropean studies as there is a limited availability of information and the majority of existingmonitoring programs focus on species that are not generally present in Mediterranean waters egAtlantic cod [828588] That being said there is evidence that suggests a yield increase of fishpopulations at wind farms as opposed to the simple attraction model previously hypothesized [8586]This is of particular importance for the Mediterranean as levels of fishing are unsustainable and mostfish stocks are in decline [71] The possibility for creating de facto marine protected areas (MPAs) due tofishing restrictions imposed within OWFs is an interesting aspect in the developments of OWFs in theMediterranean Sea It is clear that well protected MPAs in the Mediterranean result in significantlyhigher biomass than those with no or minimal protection [90] although many Mediterranean MPAslack adequate protection [91] Enforcement of fishing restrictions in Mediterranean MPAs is a difficultissue but the benefit associated with designating an area within a series of fixed structures is thatfishing regulations may be easier to enforce Benthic fishermen are less willing to drag their trawlinggear within turbines as they risk entanglement and there is a potential to monitor fishing activity ofstatic and recreational fishermen by using fixed cameras It is worth noting however that displacementof fishing effort is a serious concern for the management of reduced fishing effort regions [92]The production of sound by many fish species for communication during spawning periods means itis also essential for policy makers to identify fish spawning grounds during environmental impactassessments with the aim of restricting OWF construction in these noise-sensitive areas [93]

34 Potential Effects of Mediterranean Benthic Communities

The Mediterranean harbors many important benthic habitats including vermetid reefs coralligenicconcentrations shallow sublittoral rock seamounts deep-sea coral reefs and abyssal plains [9495]The shallow sub-littoral sediment is a particularly valuable habitat for the Mediterranean benthos as itis the preferred habitat of the endemic seagrass Posidonia oceanica listed as a priority natural habitatunder Annex 1 of the EC Habitats Directive (243EEC on the Conservation of Natural Habitatsand of Wild Fauna and Flora) due to its endemism high productivity and provision of ecosystemservices [9697] Favorable substrate conditions for OWF construction throughout Europe is typicallysoft sediment areas and the piling and drilling of foundations and monopile jackets constitutes the mostdirect impact to the marine environment As they favor similar habitats required for the constructionof OWFs Posidonia beds are at risk from direct physical destruction sedimentation and changes inhydrographic regimes Conversely construction may prevent local trawling and therefore decrease theamount of destructive fishing methods that typically reduces Posidonia coverage [98] Any plans forOWFs in the Mediterranean Sea will have to be carefully designed around the distribution of Posidoniato ensure the correct conservation practices for this endemic priority species

Other impacts to soft sediment communities from pre-construction states include changes inregional current regimes causing shifts in macro-benthic assemblages on a localized scale [99100]Studies have shown negative correlations between distance from turbines and grain sizes in the vicinityof turbines (measured from a distance from turbine of 15 m to 200 m) in the Belgian part of the NorthSea which were also positively correlated with increases in organic matter and a shift in species

J Mar Sci Eng 2016 4 18 10 of 17

assemblages The closer to the turbine the soft sediment community samples were taken the greaterthe increase in macrobenthic density and diversity [99]

Although changes in soft-sediment in-fauna are likely to be associated with wind farmconstruction the most direct affect is the addition of hard substratum to the environment Ecosystemshifts occur from changes in the existing soft sediment shifts and the addition of hard substratum ina habitat previously void of available settlement substratum Recruitment and colonization of novelartificial habitats provided by turbine foundations increases the structural complexity and productivityof an environment previously low in in-fauna diversity and density [101ndash110]

Research at an offshore research platform in the German Bight indicated that 35 times moremacro-zoobenthos biomass was associated with the additional hard substratum than the equivalentarea of soft benthic sediment [81] The increase in macro-zoobenthos biomass may appearbeneficial in regard to productivity yet in many cases species assemblages associated with artificialstructures differ from the environment replaced and show lower levels of diversity than natural rockequivalents [81110] Long-term effects of ecosystem shifts are unknown and species assemblagesare influenced by many parameters including material and texture of offshore structures larvalsupply oceanographic conditions temperature salinity and water depth [111] The number ofdefining parameters involved in influencing the spatial and temporal colonization of offshore artificialstructures highlights the need for extensive area-specific research and long-tem in situ experiments tofully understand regional implications of OWFs

With regard to the Mediterranean the limited investigative work into epibenthic colonization hasfocused on concrete artificial reefs [112ndash114] or rock anthropogenic structures [115116] Most studiesareas focus on the Northwestern region of the Mediterranean with the exception of two studies inTurkey and Israel [117118] Only two studies have investigated an offshore steel structure in theMediterranean [117118] Dominating species of epibenthic assemblages varied depending on thelocation and duration of monitoring program which ranged from 11 months to 20 years Most studiescited the initial establishment of Hydozoa Bryozoa and Serpulidae [112117ndash120] In several studiesinitial colonization was followed with the establishment and dominance of the commercially farmedMytilus galloprovincialis [112115119120] However the establishment of mussel beds on artificialstructures in the Mediterranean may be highly localized as several artificial structures showed no suchdominance [117121ndash123] or highly variable results [124] The only long-term data set on a concreteartificial reef (20 years) reported five distinct phases of species assemblage dominance of pioneerspecies mussel dominance mussel regression mussels absence and finally dominance of bryozoanbio-constructions [125] Differences in the material used for offshore structures may have a significanteffect on climax community composition the two offshore steel study sites in the Mediterraneanoffshore steel structures were both dominated by bivalves after 52 and 70 months [119121]

The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonizationof artificial substrata in the Mediterranean by alien species [122127] mean that wind farms may also actas benthic ldquostepping stonesrdquo that facilitate range extension of alien species within the Mediterraneanmarine environment which in turn may potentially reduce the biodiversity of the basin [111128]Due to the apparent locality factor of benthic colonization communites small-scale pilot studies areessential for understanding whether windfarms will proliferate alien species at potential wind farmlocations The use of before-after control-impact studies by policy makers is strongly recommended

35 Potential Effects of Mediterranean Planktonic Communities

The oxygen rich oligotrophic waters of the semi-enclosed Mediterranean produce a lownutrient availability that is however generally intensified along both a west-east and north-southdirection [129] There is nevertheless a high spatial heterogeneity in the distribution of planktonthroughout the Mediterranean Sea due to complex hydrodynamic circulation patterns formingmultiple gyres and upwelling systems [130] Most marine invertebrate and fish species havea planktonic larval stage therefore it is crucial to understand any effects OWFs may have on planktonic

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 10 of 17

assemblages The closer to the turbine the soft sediment community samples were taken the greaterthe increase in macrobenthic density and diversity [99]

Although changes in soft-sediment in-fauna are likely to be associated with wind farmconstruction the most direct affect is the addition of hard substratum to the environment Ecosystemshifts occur from changes in the existing soft sediment shifts and the addition of hard substratum ina habitat previously void of available settlement substratum Recruitment and colonization of novelartificial habitats provided by turbine foundations increases the structural complexity and productivityof an environment previously low in in-fauna diversity and density [101ndash110]

Research at an offshore research platform in the German Bight indicated that 35 times moremacro-zoobenthos biomass was associated with the additional hard substratum than the equivalentarea of soft benthic sediment [81] The increase in macro-zoobenthos biomass may appearbeneficial in regard to productivity yet in many cases species assemblages associated with artificialstructures differ from the environment replaced and show lower levels of diversity than natural rockequivalents [81110] Long-term effects of ecosystem shifts are unknown and species assemblagesare influenced by many parameters including material and texture of offshore structures larvalsupply oceanographic conditions temperature salinity and water depth [111] The number ofdefining parameters involved in influencing the spatial and temporal colonization of offshore artificialstructures highlights the need for extensive area-specific research and long-tem in situ experiments tofully understand regional implications of OWFs

With regard to the Mediterranean the limited investigative work into epibenthic colonization hasfocused on concrete artificial reefs [112ndash114] or rock anthropogenic structures [115116] Most studiesareas focus on the Northwestern region of the Mediterranean with the exception of two studies inTurkey and Israel [117118] Only two studies have investigated an offshore steel structure in theMediterranean [117118] Dominating species of epibenthic assemblages varied depending on thelocation and duration of monitoring program which ranged from 11 months to 20 years Most studiescited the initial establishment of Hydozoa Bryozoa and Serpulidae [112117ndash120] In several studiesinitial colonization was followed with the establishment and dominance of the commercially farmedMytilus galloprovincialis [112115119120] However the establishment of mussel beds on artificialstructures in the Mediterranean may be highly localized as several artificial structures showed no suchdominance [117121ndash123] or highly variable results [124] The only long-term data set on a concreteartificial reef (20 years) reported five distinct phases of species assemblage dominance of pioneerspecies mussel dominance mussel regression mussels absence and finally dominance of bryozoanbio-constructions [125] Differences in the material used for offshore structures may have a significanteffect on climax community composition the two offshore steel study sites in the Mediterraneanoffshore steel structures were both dominated by bivalves after 52 and 70 months [119121]

The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonizationof artificial substrata in the Mediterranean by alien species [122127] mean that wind farms may also actas benthic ldquostepping stonesrdquo that facilitate range extension of alien species within the Mediterraneanmarine environment which in turn may potentially reduce the biodiversity of the basin [111128]Due to the apparent locality factor of benthic colonization communites small-scale pilot studies areessential for understanding whether windfarms will proliferate alien species at potential wind farmlocations The use of before-after control-impact studies by policy makers is strongly recommended

35 Potential Effects of Mediterranean Planktonic Communities

The oxygen rich oligotrophic waters of the semi-enclosed Mediterranean produce a lownutrient availability that is however generally intensified along both a west-east and north-southdirection [129] There is nevertheless a high spatial heterogeneity in the distribution of planktonthroughout the Mediterranean Sea due to complex hydrodynamic circulation patterns formingmultiple gyres and upwelling systems [130] Most marine invertebrate and fish species havea planktonic larval stage therefore it is crucial to understand any effects OWFs may have on planktonic

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 11 of 17

communities There has been much speculation about the impacts caused by OWFs in relationto plankton [6107110] Evidently at some scale any offshore construction will have an effect onlocal hydrographic regimes [131] however the extent that this will affect upwellingdownwellingepisodes and thus potentially phytoplankton blooms is currently unknown Analytical modelsindicate that OWFs affect surface gravity waves underneath rotor blades [132133] and there is muchspeculation in the literature as to the impacts any hydrographic changes will have on planktonnektonaggregations [19] OWFs may also affect planktonic populations by providing hard substrata thatfacilitate planktonic connectivity through larval settlement during dispersal processes [134ndash136]The presence of available hard substratum from wind turbines for the recruitment and settlementof pelagic larvae have the potential to extend passive larval connectivity across biogeographicboundaries [134] It is noted that there is a scarcity of information in the literature regarding theimpacts OWFs will have on planktonic communities

4 Conclusions

As the likelihood of Mediterranean OWFs increases there is an ever-growing need to assess thebiological costs and benefits of OWFs in the region The aims of this horizon-scanning review weretwo-fold firstly to identify areas likely to be considered for the development of OWFs within theregion and secondly to identify the biological impacts of these developments

The five OWF hotspots are identified as the Gulf of Lion the North Adriatic Sea the Gulfs ofHammamet and Gabegraves the Gulf of Sidra and the Nile Delta Understanding the species habitatsand taxa that are likely to be affected by the construction and operation of OWFs in these regionsand the wider Mediterranean region will assist developers and policy makers with future spatialplanning decisions regarding OWFs within the Mediterranean Furthermore the advancement andimplementation of floating wind turbine technology may diminish many of the above mentionedeffects which from this point of view is a very promising perspective for the near future

Acknowledgments This work was supported by project ldquoTowards Coast to Coast NETworks of marine protectedareas (from the shore to the high and deep sea) coupled with sea-based wind energy potentialrdquo (COCONET)from European Communityrsquos Seventh Framework Programme (FP72007ndash2013) under Grant Agreement No287844 project

Author Contributions LB conceived the investigation EV and TS analyzed model output data LB SD SRCA and MV-L performed and analyzed data from the literature review LB MJA and JMH-S interpretedthe results LB MJA and JMH-S wrote the paper

Conflicts of Interest The authors declare no conflict of interest

References

1 Kermeli K Graus WHJ Worrell E Energy efficiency improvement potentials and a low energy demandscenario for the global industrial sector Energy Effic 2014 7 987ndash1011 [CrossRef]

2 Esseghir A Haouaoui Khouni L Economic growth energy consumption and sustainable developmentThe case of the Union for the Mediterranean countries Energy 2014 71 218ndash225 [CrossRef]

3 Cartalis C Synodinou A Proedrou M Tsangrassoulis A Santamouris M Modifications in energydemand in urban areas as a result of climate changes An assessment for the southeast Mediterranean regionEnergy Convers Manag 2001 42 1647ndash1656 [CrossRef]

4 Tsikalakis A Tomtsi T Hatziargyriou ND Poullikkas A Malamatenios C Giakoumelos EJaouad OC Chenak A Fayek A Matar T et al Review of best practices of solar electricity resourcesapplications in selected Middle East and North Africa (MENA) countries Renew Sustain Energy Rev2011 15 2838ndash2849 [CrossRef]

5 European Wind Energy Association (EWEA) Corbetta G Pineda I Wilkes J The European Offshore WindIndustrymdashKey Trends and Statistics 1st Half 2014 The European Wind Energy Association Brussels Belgium2014 p 6

6 European Environment Agency (EEA) Europersquos Onshore and Offshore Wind Energy Potential An Assessment ofEnvironmental and Economic Constraints EEA Copenhagen Denmark 2009

J Mar Sci Eng 2016 4 18 12 of 17

7 Bilgili M Yasar A Simsek E Offshore wind power development in Europe and its comparison withonshore counterpart Renew Sustain Energy Rev 2011 15 905ndash915 [CrossRef]

8 Jacques S Kreutzkamp P Joseph P Seanergy 2020 Analysis of PlannedSuggested Offshore ElectricityInfrastructure Relatively to Existing International MSP Instruments 2011 European Wind Energy AssociationBrussels Belgium 2011

9 European Wind Energy Association (EWEA) Moccia J Arapogianni A Wilkes J Kjaer C Gruet RPure Power Wind Energy Targets for 2020 and 2030 European Wind Energy Association Brussels Belgium2011 p 96

10 De Decker J Kreutzkamp P Joesph P Woyte A Cowdroy S Warland L Svendsen H Voumllker JFunk C Peinil H et al Offshore Electricity Grid Infrastructure in Europe OffshoreGrid Final ReportOffshoreGrid Brussels Belgium 2011

11 Coll M Piroddi C Steenbeek J Kaschner K Ben Rais Lasram F Aguzzi J Ballesteros E Bianchi CNCorbera J Dailianis T et al The biodiversity of the Mediterranean Sea Estimates patterns and threatsPLoS ONE 2010 5 e11842 [CrossRef] [PubMed]

12 Zenetos A Gofas S Morri C Rosso A Violanti D Garcia Raso JE Cinar ME Almogi-Labin AAtes AS Azzurro E et al Alien species in the Mediterranean Sea by 2012 A contribution to theapplication of European Unionrsquos Marine Strategy Framework Directive (MSFD) Part 2 Introduction trendsand pathways Mediterr Mar Sci 2012 13 [CrossRef]

13 Micheli F Halpern BS Walbridge S Ciriaco S Ferretti F Fraschetti S Lewison R Nykjaer LRosenberg AA Cumulative human impacts on mediterranean and black sea marine ecosystems Assessingcurrent pressures and opportunities PLoS ONE 2013 8 e79889 [CrossRef] [PubMed]

14 Papadopoulos A Katsafados P Verification of operational weather forecasts from the POSEIDON systemacross the Eastern Mediterranean Nat Hazards Earth Syst Sci 2009 9 1299ndash1306 [CrossRef]

15 Papadopoulos A Kallos G Katsafados P Nickovic S The Poseidon weather forecasting systemAn overview Glob Atmos Ocean Syst 2002 8 219ndash237 [CrossRef]

16 Papadopoulos A Korres G Katsafados P Ballas D Perivoliotis L Nittis K Dynamic downscaling ofthe ERA-40 data using a mesoscale meteorological model Mediterr Mar Sci 2011 12 [CrossRef]

17 Uppala SM KAringllberg PW Simmons AJ Andrae U Bechtold VDC Fiorino M Gibson JKHaseler J Hernandez A Kelly GA et al The ERA-40 re-analysis Q J R Meteorol Soc 2005 1312961ndash3012 [CrossRef]

18 Soukissian TH Papadopoulos A Effects of different wind data sources in offshore wind power assessmentRenew Energy 2015 77 101ndash114 [CrossRef]

19 Desholm M Kahlert J Avian collision risk at an offshore wind farm Biol Lett 2005 1 296ndash298 [CrossRef][PubMed]

20 Scott BE Langton R Philpott E Waggitt JJ Seabirds and Marine Renewables Are We Asking the RightQuestions In Marine Renewable Energy Technology and Environmental Interactions Shields MA Payne AILEds Springer Netherlands Dordrecht The Netherlands 2014 pp 81ndash92

21 The IUCN Red List of Threatened Species Version 20142 Available online httpwww iucnredlistorg(accessed on 28 August 2014)

22 United Nations Environment Programme-Mediterranean Action Plan (UNEP-MAP) Protocol ConcerningSpecially Protected Areas and Biological Diversity in the Mediterranean UNEPMap Publications Athens Greece1999 p 3

23 Cooper J Baccetti N Belda EJ Borg JJ Oro D Papaconstantinou C Saacutenchez A Seabird mortalityfrom longline fishing in the Mediterranean Sea and Macaronesian waters A review and a way forwardSci Mar 2003 67 57ndash64 [CrossRef]

24 Bourgeois K Vidal E The endemic Mediterranean yelkouan shearwater Puffinus yelkouan Distributionthreats and a plea for more data Oryx 2008 42 187ndash194 [CrossRef]

25 Thibault JC Zotier R Guyot I Bretagnolle V Recent trends in breeding marine birds of the Mediterraneanregion with special reference to Corsica Colon Waterbirds 1996 19 31ndash40 [CrossRef]

26 Donald PF Sanderson FJ Burfield IJ Bierman SM Gregory RD Waliczky Z Internationalconservation policy delivers benefits for birds in Europe Science 2007 317 810ndash813 [CrossRef] [PubMed]

27 Oro D Effects of trawler discard availability on egg laying and breeding success in the lesser black-backedgull Larus fuscus in the western Mediterranean Mar Ecol Prog Ser 1996 132 43ndash46 [CrossRef]

J Mar Sci Eng 2016 4 18 13 of 17

28 Oro D Ruiz X Exploitation of trawler discards by breeding seabirds in the north-western MediterraneanDifferences between the Ebro Delta and the Balearic Islands areas ICES J Mar Sci 1997 54 695ndash707[CrossRef]

29 Bicknell AWJ Oro D Camphuysen K Votier SC Potential consequences of discard reform for seabirdcommunities J Appl Ecol 2013 50 649ndash658 [CrossRef]

30 Bradbury G Trinder M Furness B Banks AN Caldow RWG Hume D Mapping seabird sensitivityto offshore wind farms PLoS ONE 2014 9 e106366 [CrossRef] [PubMed]

31 Furness RW Wade HM Masden EA Assessing vulnerability of marine bird populations to offshorewind farms J Environ Manag 2013 119 56ndash66 [CrossRef] [PubMed]

32 Garthe S Huumlppop O Scaling possible adverse effects of marine wind farms on seabirds Developing andapplying a vulnerability index J Appl Ecol 2004 41 724ndash734 [CrossRef]

33 Gallo-Orsi U Species Action Plans for the conservation of seabirds in the Mediterranean Sea Audouinrsquosgull Balearic shearwater and Mediterranean shag Sci Mar 2003 67 (Suppl 2) 47ndash55 [CrossRef]

34 Wilcove DS Wikelski M Going going gone Is animal migration disappearing PLoS Biol 2008 6 e188[CrossRef] [PubMed]

35 Boere GC Stroud DA The Flyway Concept What It Is and What It Isnrsquot The Stationery Office EdinburghUK 2006 pp 40ndash47

36 Denac D Schneider-Jacoby M Stumberger B Adriatic Flyway Closing the Gap in Bird ConservationEuronatur Liboa Portugal 2010

37 Alerstam T Pettersson SG Why do migrating birds fly along coastlines J Theor Biol 1977 65 699ndash712[CrossRef]

38 Pennycuick CJ Soaring behavior and performance of some east African birds observed from a motor-gliderIBIS 1972 114 178ndash218 [CrossRef]

39 Bijlsma RG Bottleneck Areas for Migratory Birds in the Mediterranean Region An Assessment of the Problems andRecommendations for Action ICBP Cambridge UK 1987 Volume 18

40 Kirby JS Stattersfield AJ Butchart SHM Evans MI Grimmett RFA Jones VR OrsquoSullivan JTucker GM Newton I Key conservation issues for migratory land- and waterbird species on the worldrsquosmajor flyways Bird Conserv Int 2008 18 S49ndashS73 [CrossRef]

41 Jourdain E Gauthier-Clerc M Bicout D Sabatier P Bird Migration Routes and Risk for PathogenDispersion into Western Mediterranean Wetlands Emerg Infect Dis 2007 13 365ndash372 [CrossRef] [PubMed]

42 Huumlppop O Dierschke J Exo K-M Fredrich E Hill R Bird migration studies and potential collision riskwith offshore wind turbines IBIS 2006 148 90ndash109 [CrossRef]

43 Biebach H Biebach I Friedrich W Heine G Partecke J Schmidl D Strategies of passerine migrationacross the Mediterranean Sea and the Sahara Desert A radar study IBIS 2000 142 623ndash634 [CrossRef]

44 Alerstam T Lindstroumlm Aring Optimal bird migration The relative importance of time energy and safetyIn Bird Migration Gwinner PDE Ed Springer Berlin Germany 1990 pp 331ndash351

45 Gschweng M Kalko EKV Querner U Fiedler W Berthold P All across Africa Highly individualmigration routes of Eleonorarsquos falcon Proc Biol Sci 2008 275 2887ndash2896 [CrossRef] [PubMed]

46 Wildfowl and Wetlands Trust (WWT) Strategic assessment of collision risk of Scottish offshore wind farms tomigrating birds Scottish Marine and Freshwater Science Scottish Government Edinburgh UK 2014 Volume 5

47 Masden EA Reeve R Desholm M Fox AD Furness RW Haydon DT Assessing the impact ofmarine wind farms on birds through movement modelling J R Soc Interface 2012 9 2120ndash2130 [CrossRef][PubMed]

48 Poot H Ens BJ de Vries H Donners MA Wernand MR Marquenie JM Green light for nocturnallymigrating birds Ecol Soc 2008 13 47

49 Saidur R Rahim NA Islam MR Solangi KH Environmental impact of wind energy Renew SustainEnergy Rev 2011 15 2423ndash2430 [CrossRef]

50 Notarbartolo-di-Sciara G Agardy T Hyrenbach D Scovazzi T van Klaveren P The Pelagos Sanctuaryfor Mediterranean marine mammals Aquat Conserv Mar Freshw Ecosyst 2008 18 367ndash391 [CrossRef]

51 Frantzis A Nikolaou O Bompar JM Cammedda A Humpback whale (Megaptera novaeangliae)occurrence in the Mediterranean Sea J Cetacean Res Manag 2004 6 25ndash28

52 Notarbartolo-Di-Sciara G Zanardelli M Jahoda M Panigada S Airoldi S The fin whaleBalaenoptera physalus (L 1758) in the Mediterranean Sea Mamm Rev 2003 33 105ndash150 [CrossRef]

J Mar Sci Eng 2016 4 18 14 of 17

53 Cantildeadas A Sagarminaga R The Northeastern Alboran Sea an important breeding and feeding groundfor the long-finned pilot whale (Globicephala Melas) in the Mediterranean Sea Mar Mammal Sci 2000 16513ndash529 [CrossRef]

54 Frantzis A Airoldi S Notarbartolo-di-Sciara G Johnson C Mazzariol S Inter-basin movements ofMediterranean sperm whales provide insight into their population structure and conservation Deep SeaRes I 2011 58 454ndash459 [CrossRef]

55 Bearzi G Fortuna CM Reeves RR Ecology and conservation of common bottlenose dolphins Tursiopstruncatus in the Mediterranean Sea Mammal Rev 2009 39 92ndash123 [CrossRef]

56 Dendrinos P Karamanlidis AA Kotomatas S Paravas V Adamantopoulou S Report of a NewMediterranean monk seal (Monachus monachus) breeding colony in the Aegean Sea Greece Aquat Mamm2008 34 355ndash361 [CrossRef]

57 Gomercic T Huber D Gomercic M Gomercic H Presence of the Mediterranean monk seal(Monachus monachus) in the Croatian part of the Adriatic Sea Aquat Mamm 2011 37 243ndash247 [CrossRef]

58 Thomsen F Luumldemann K Kafemann R Piper W Effects of Offshore Wind Farm Noise on Marine Mammalsand Fish Germany on Behalf of COWRIE Ltd Hamburg Germany 2006

59 Madsen P Wahlberg M Tougaard J Lucke K Tyack P Wind turbine underwater noise and marinemammals Implications of current knowledge and data needs Mar Ecol Prog Ser 2006 309 279ndash295[CrossRef]

60 Bergstroumlm L Kautsky L Malm T Rosenberg R Wahlberg M Capetillo NAring Wilhelmsson D Effectsof offshore wind farms on marine wildlifemdashA generalized impact assessment Environ Res Lett 2014 9034012 [CrossRef]

61 Bailey H Clay G Coates EA Lusseau D Senior B Thompson PM Using T-PODs to assess variationsin the occurrence of coastal bottlenose dolphins and harbor porpoises Aquat Conserv Mar Freshw Ecosyst2010 20 150ndash158 [CrossRef]

62 Carstensen J Henriksen OD Teilmann J Impacts of offshore wind farm construction on harbor porpoisesAcoustic monitoring of echo-location activity using porpoise detectors (T-PODs) Mar Ecol Prog Ser2006 321 295ndash308 [CrossRef]

63 Teilmann J Carstensen J Negative long term effects on harbor porpoises from a large scale offshore windfarm in the BalticmdashEvidence of slow recovery Environ Res Lett 2012 7 045101 [CrossRef]

64 Scheidat M Tougaard J Brasseur S Carstensen J van Polanen Petel T Teilmann J Reijnders P Harbourporpoises (Phocoena phocoena) and wind farms A case study in the Dutch North Sea Environ Res Lett2011 6 025102 [CrossRef]

65 Russell DJF Brasseur SM Thompson D Hastie GD Janik VM Aarts G McClintock BTMatthiopoulos J Moss SEW McConnell B Marine mammals trace anthropogenic structures at seaCurr Biol 2014 24 R638ndashR639 [CrossRef] [PubMed]

66 Abdulla A Maritime Traffic Effects on Biodiversity in the Mediterranean Sea Review of Impacts Priority Areas andMitigation Measures IUCN Gland Switzerland 2008 Volume 1

67 Bailey H Senior B Simmons D Rusin J Picken G Thompson PM Assessing underwater noise levelsduring pile-driving at an offshore windfarm and its potential effects on marine mammals Mar Pollut Bull2010 60 888ndash897 [CrossRef] [PubMed]

68 David JA Likely sensitivity of bottlenose dolphins to pile-driving noise Water Environ J 2006 20 48ndash54[CrossRef]

69 Tzanatos E Dimitriou E Papaharisis L Roussi A Somarakis S Koutsikopoulos C Principalsocio-economic characteristics of the Greek small-scale coastal fishermen Ocean Coast Manag 2006 49511ndash527 [CrossRef]

70 Malak DA Overview of the Conservation Status of the Marine Fishes of the Mediterranean Sea IUCN GlandSwitzerland 2011

71 Vasilakopoulos P Maravelias CD Tserpes G The alarming decline of Mediterranean fish stocks Curr Biol2014 24 1643ndash1648 [CrossRef] [PubMed]

72 Debusschere E Coensel BD Vandendriessche S Botteldooren D Hostens K Vincx M Degraer SEffects of offshore wind farms on the early life stages of Dicentrarchus Labrax In The Effects of Noise on AquaticLife II Popper AN Hawkins A Eds Springer New York NY USA 2016 pp 197ndash204

73 Wahlberg M Westerberg H Hearing in fish and their reactions to sounds from offshore wind farmsMar Ecol Prog Ser 2005 288 295ndash309 [CrossRef]

J Mar Sci Eng 2016 4 18 15 of 17

74 Sigray P Andersson MH Particle motion measured at an operational wind turbine in relation to hearingsensitivity in fish J Acoust Soc Am 2011 130 200ndash207 [CrossRef] [PubMed]

75 Radford AN Kerridge E Simpson SD Acoustic communication in a noisy world Can fish compete withanthropogenic noise Behav Ecol 2014 25 1022ndash1030 [CrossRef]

76 Tricas T Gill AB Effects of EMFs from Undersea Power Cables on Elasmobranchs and Other Marine Species USDept of the Interior Camirillo CA USA 2011 p 426

77 Gill AB Taylor H The Potential Effects of Electromagnetic Fields Generated by Cabling between Offshore WindTurbines upon Elasmobranch Fishes Countryside Council for Wales and University of Liverpool Bangor UK2001 p 60

78 Oumlhman MC Sigray P Westerberg H Offshore windmills and the effects of electromagnetic fields on fishAMBIO 2007 36 630ndash633 [CrossRef]

79 Gill AB Bartlett M Thomsen F Potential interactions between diadromous fishes of UK conservationimportance and the electromagnetic fields and subsea noise from marine renewable energy developmentsJ Fish Biol 2012 81 664ndash695 [CrossRef] [PubMed]

80 Westerberg H Lagenfelt I Sub-sea power cables and the migration behaviour of the European eelFish Manag Ecol 2008 15 369ndash375 [CrossRef]

81 Krone R Gutow L Joschko TJ Schroumlder A Epifauna dynamics at an offshore foundationmdashImplicationsof future wind power farming in the North Sea Mar Environ Res 2013 85 1ndash12 [CrossRef] [PubMed]

82 Reubens JT Braeckman U Vanaverbeke J van Colen C Degraer S Vincx M Aggregation at windmillartificial reefs CPUE of Atlantic cod (Gadus morhua) and pouting (Trisopterus luscus) at different habitats inthe Belgian part of the North Sea Fish Res 2013 139 28ndash34 [CrossRef]

83 Wilhelmsson D Malm T Oumlhman MC The influence of offshore windpower on demersal fish ICES JMar Sci 2006 63 775ndash784 [CrossRef]

84 Wilson JC Elliott M The habitat-creation potential of offshore wind farms Wind Energy 2009 12 203ndash212[CrossRef]

85 Reubens JT Degraer S Vincx M The ecology of benthopelagic fishes at offshore wind farms A synthesisof 4 years of research Hydrobiologia 2014 727 121ndash136 [CrossRef]

86 De Troch M Reubens JT Heirman E Degraer S Vincx M Energy profiling of demersal fish A case-studyin wind farm artificial reefs Mar Environ Res 2013 92 224ndash233 [CrossRef] [PubMed]

87 Reubens JT de Rijcke M Degraer S Vincx M Diel variation in feeding and movement patterns ofjuvenile Atlantic cod at offshore wind farms J Sea Res 2014 85 214ndash221 [CrossRef]

88 Bergstroumlm L Sundqvist F Bergstrm U Effects of an offshore wind farm on temporal and spatial patternsin the demersal fish community Mar Ecol Prog Ser 2013 485 199ndash210 [CrossRef]

89 Wilhelmsson D Langhamer O The influence of fisheries exclusion and addition of hard substrata onfish and crustaceans In Marine Renewable Energy Technology and Environmental Interactions Shields MAPayne AIL Eds Springer Netherlands Dordrecht The Netherlands 2014 pp 49ndash60

90 Guidetti P Baiata P Ballesteros E di Franco A Hereu B Macpherson E Micheli F Pais A Panzalis PRosenberg AA et al Large-scale assessment of Mediterranean marine protected areas effects on fishassemblages PLoS ONE 2014 9 e91841 [CrossRef] [PubMed]

91 Montefalcone M Albertelli G Morri C Parravicini V Bianchi CN Legal protection is not enoughPosidonia oceanica meadows in marine protected areas are not healthier than those in unprotected areas of thenorthwest Mediterranean Sea Mar Pollut Bull 2009 58 515ndash519 [CrossRef] [PubMed]

92 Halpern BS Gaines SD Warner RR Confounding effects of the export of production and thedisplacement of fishing effort from marine reserves Ecol Appl 2004 14 1248ndash1256 [CrossRef]

93 Slabbekoorn H Bouton N van Opzeeland I Coers A ten Cate C Popper AN A noisy springThe impact of globally rising underwater sound levels on fish Trends Ecol Evol 2010 25 419ndash427 [CrossRef][PubMed]

94 Danovaro R Company JB Corinaldesi C DrsquoOnghia G Galil B Gambi C Gooday AJLampadariou N Luna GM Morigi C et al Deep-sea biodiversity in the Mediterranean Sea The knownthe unknown and the unknowable PLoS ONE 2010 5 e11832 [CrossRef] [PubMed]

95 Mo G Agnesi S Evans D Populus J Tunesi L Mediterranean benthic EUNIS habitats Structuralconsiderations and lessons learned from mapping Rev Investig Mar 2012 19 48ndash50

J Mar Sci Eng 2016 4 18 16 of 17

96 Vassallo P Paoli C Rovere A Montefalcone M Morri C Bianchi CN The value of the seagrassPosidonia oceanica A natural capital assessment Mar Pollut Bull 2013 75 157ndash167 [CrossRef] [PubMed]

97 Jackson EL Rees SE Wilding C Attrill MJ Use of a seagrass residency index to apportion commercialfishery landing values and recreation fisheries expenditure to seagrass habitat service Conserv Biol 2015 29899ndash909 [CrossRef] [PubMed]

98 Sanchezjerez P Effect of an artificial reef in Posidonia meadows on fish assemblage and diet ofDiplodus annularis ICES J Mar Sci 2002 59 S59ndashS68 [CrossRef]

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100 De Backer A van Hoey G Coates D Vanaverbeke J Hostens K Similar diversity-disturbance responsesto different physical impacts Three cases of small-scale biodiversity increase in the Belgian part of the NorthSea Mar Pollut Bull 2014 84 251ndash262 [CrossRef] [PubMed]

101 Birklund J Petersen AH Development of the Fouling Community on Turbine Foundations and Scour Protectionsin Nysted Offshore Wind Farm 2003 Report Energi E2 AS DHI Water and Environment Hoslashrsholm Denmark2004

102 Kerckhof F Norro A Jacques T Degraer S Early colonization of a concrete offshore windmill foundationby marine biofouling on the Thornton Bank (southern North Sea) In Offshore Wind Farms in the Belgian Partof the North Sea State of the Art after Two Years of Environmental Monitoring Royal Belgian Institute of NaturalSciences Brussel Belgium 2009

103 Kerckhof F Rumes B Norro A Jacques TG Degraer S Seasonal variation and vertical zonation ofthe marine biofouling on a concrete offshore windmill foundation on the Thornton Bank (southern NorthSea) In Offshore Wind Farms in the Belgian Part of the North Sea State of the Art after Two Years of EnvironmentalMonitoring Royal Belgian Institute of Natural Sciences Brussel Belgium 2010

104 Kerckhof F Rumes B Jacques T Degraer S Norro A Early development of the subtidal marinebiofouling on a concrete offshore windmill foundation on the Thornton Bank (southern North Sea) Firstmonitoring results Underw Technol 2010 29 137ndash149 [CrossRef]

105 Langhamer O Wave Energy Conversion and the Marine Environment Colonization Patterns and HabitatDynamics PhD Thesis Uppsala University Uppsala Sweden 2009

106 Lindeboom HJ Kouwenhoven HJ Bergman MJN Bouma S Brasseur S Daan R Fijn RCde Haan D Dirksen S van Hal R Short-term ecological effects of an offshore wind farm in the Dutchcoastal zone a compilation Environ Res Lett 2011 6 035101 [CrossRef]

107 Maar M Bolding K Petersen JK Hansen JLS Timmermann K Local effects of blue mussels aroundturbine foundations in an ecosystem model of Nysted off-shore wind farm Denmark J Sea Res 2009 62159ndash174 [CrossRef]

108 Shi W Park HC Baek JH Kim CW Kim YC Shin HK Study on the marine growth effect on thedynamic response of offshore wind turbines Int J Precis Eng Manuf 2012 13 1167ndash1176 [CrossRef]

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110 Wilhelmsson D Malm T Fouling assemblages on offshore wind power plants and adjacent substrataEstuar Coast Shelf Sci 2008 79 459ndash466 [CrossRef]

111 Langhamer O Artificial reef effect in relation to offshore renewable energy conversion State of the artSci World J 2012 2012 [CrossRef] [PubMed]

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114 Sinis AI Chintiroglou CC Stergiou KI Preliminary results from the establishment of experimentalartificial reefs in the N Aegean Sea (Chalkidiki Greece) Belg J Zool 2000 130 143ndash147

115 Airoldi L Bulleri F Anthropogenic disturbance can determine the magnitude of opportunistic speciesresponses on marine urban infrastructures PLoS ONE 2011 6 e22985 [CrossRef] [PubMed]

116 Bulleri F Airoldi L Artificial marine structures facilitate the spread of a non-indigenous green algaCodium fragile ssp tomentosoides in the north Adriatic Sea J Appl Ecol 2005 42 1063ndash1072 [CrossRef]

J Mar Sci Eng 2016 4 18 17 of 17

117 Goren M Development of benthic community on artificial substratum at Ashdod (Eastern Mediterranean)Oceanol Acta 1980 3 275ndash283

118 Kocak F Ergen Z Ccedilinar ME Fouling organisms and their developments in a polluted and an unpollutedmarina in the Aegean Sea (Turkey) Ophelia 1999 50 1ndash20 [CrossRef]

119 Relini G Relini M Montanari M An offshore buoy as a small artificial island and a fish-aggregatingdevice (FAD) in the Mediterranean In Island Ocean and Deep-Sea Biology Jones MB Azevedo JMNNeto AI Costa AC Martins AMF Eds Springer Netherlands Dordrecht The Netherlands 2000pp 65ndash80

120 Moreno I Roca I Rentildeones O Coll J Salamanca M Artificial reef program in Balearic waters (westernMediterranean) Bull Mar Sci 1994 55 667ndash671

121 Relini G Tixi F Relini M Torchia G The macrofouling on offshore platforms at Ravenna Int BiodeteriorBiodegrad 1998 41 41ndash55 [CrossRef]

122 Badalamenti F Are artificial reefs comparable to neighbouring natural rocky areas A mollusc case study inthe Gulf of Castellammare (NW Sicily) ICES J Mar Sci 2002 59 S127ndashS131 [CrossRef]

123 Relini G Zamboni N Tixi F Torchia G Patterns of sessile Macrobenthos community development on anartificial reef in the gulf of genoa (Northwestern Mediterranean) Bull Mar Sci 1994 55 745ndash771

124 Ponti M Fava F Perlini RA Giovanardi O Abbiati M Benthic assemblages on artificial reefs inthe northwestern Adriatic Sea Does structure type and age matter Mar Environ Res 2015 104 10ndash19[CrossRef] [PubMed]

125 Nicoletti L Marzialetti S Paganelli D Ardizzone GD Long-term changes in a benthic assemblageassociated with artificial reefs In Biodiversity in Enclosed Seas and Artificial Marine Habitats Relini GRyland J Eds Springer Netherlands Dordrecht The Netherlands 2007 pp 233ndash240

126 Galil BS Boero F Campbell ML Carlton JT Cook E Fraschetti S Gollasch S Hewitt CLJelmert A Macpherson E et al ldquoDouble troublerdquo The expansion of the Suez Canal and marine bioinvasionsin the Mediterranean Sea Biol Invasions 2014 17 973ndash976 [CrossRef]

127 Ccedilinar ME Serpulid species (Polychaeta Serpulidae) from the Levantine coast of Turkey (easternMediterranean) with special emphasis on alien species Aquat Invasions 2006 1 223ndash240 [CrossRef]

128 Adams TP Miller RG Aleynik D Burrows MT Offshore marine renewable energy devices as steppingstones across biogeographical boundaries J Appl Ecol 2014 51 330ndash338 [CrossRef]

129 Siokou-Frangou I Christaki U Mazzocchi MG Montresor M Ribera drsquoAlcalaacute M Vaqueacute D Zingone APlankton in the open Mediterranean Sea A review Biogeosciences 2010 7 1543ndash1586 [CrossRef]

130 Cerino F Bernardi Aubry F Coppola J La Ferla R Maimone G Socal G Totti C Spatial and temporalvariability of pico- nano- and microphytoplankton in the offshore waters of the southern Adriatic Sea(Mediterranean Sea) Cont Shelf Res 2012 44 94ndash105 [CrossRef]

131 Shields MA Woolf DK Grist EPM Kerr SA Jackson AC Harris RE Bell MC Beharie RWant A Osalusi E et al Marine renewable energy The ecological implications of altering thehydrodynamics of the marine environment Ocean Coast Manag 2011 54 2ndash9 [CrossRef]

132 Brostroumlm G On the influence of large wind farms on the upper ocean circulation J Mar Syst 2008 74585ndash591 [CrossRef]

133 Paskyabi MB Fer I Upper ocean response to large wind farm effect in the presence of surface gravitywaves Energy Procedia 2012 24 245ndash254 [CrossRef]

134 Adams TP Aleynik D Burrows M Larval dispersal of intertidal organisms and the influence of coastlinegeography Ecography 2014 37 698ndash710 [CrossRef]

135 Inger R Attrill MJ Bearhop S Broderick AC James Grecian W Hodgson DJ Mills C Sheehan EVotier SC Witt MJ Marine renewable energy Potential benefits to biodiversity An urgent call forresearch J Appl Ecol 2009 46 1145ndash1153 [CrossRef]

136 Miller RG Hutchison ZL Macleod AK Burrows MT Cook EJ Last KS Wilson B Marinerenewable energy development Assessing the Benthic Footprint at multiple scales Front Ecol Environ2013 11 433ndash440 [CrossRef]

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